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Filed Pursuant to Rule 424(b)(5)

File No. 333-88478

Subject to Completion, Dated April 26, 2006

Prospectus Supplement to Prospectus Dated May 22, 2002

Pioneer Natural Resources Company

 

$400,000,000

                % Senior Notes due 2018

________________________________________________________________________________

We will pay interest on the notes each May 1 and November 1. The first interest payment will be made on November 1, 2006. The notes will be unsecured senior obligations of Pioneer Natural Resources Company and will rank equally with all of our other unsecured senior indebtedness. There is no sinking fund for the notes. We may redeem the notes, in whole or in part, at any time and from time to time at the redemption price set forth under “Description of Notes— Optional Redemption” in this prospectus supplement.

Investing in the notes involves risks. See “Risk Factors” on page S-5.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the related prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

				Underwriting		Proceeds to
		Price to Public (1)		Discounts		Pioneer (1)
Per note		%		%		%
Total		$		$		$

 

(1) Plus accrued interest, if any, from May     , 2006, if settlement occurs after that date.

Delivery of the notes will be made in book-entry form on or about May      , 2006.

Sole Book-Running Joint Lead Manager

Deutsche Bank Securities

Joint Lead Manager

Morgan Stanley

Co-Managers

ABN AMRO

	Barclays

	Harris Nesbitt

The date of this prospectus supplement is April      , 2006.

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PROSPECTUS

$1,000,000,000

Pioneer Natural Resources Company

Debt Securities

        We may offer and sell securities from time to time in one or more classes or series and in amounts, at prices and on terms that we will determine at the time of the offering, with a total initial offering price of up to $1,000,000,000. Any debt securities we issue under this prospectus may be guaranteed by Pioneer Natural Resources USA, Inc., our direct wholly-owned subsidiary that we call Pioneer USA.

      We will provide specific terms of the securities to be sold by us, including any guarantee by Pioneer USA, and the methods by which we will sell them in supplements to this prospectus. You should read this prospectus and any supplement carefully before you invest. This prospectus may not be used to offer or sell securities without a prospectus supplement describing the methods and terms of the offering. We may sell the securities directly or we may distribute them through underwriters or dealers. In addition, the underwriters may overallot a portion of the securities.

      Our common stock is listed on the New York Stock Exchange under the symbol “PXD.”

       Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 22, 2002.

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ABOUT THIS PROSPECTUS

      This prospectus is part of a registration statement on Form S-3 that Pioneer and Pioneer USA filed with the Securities and Exchange Commission using a shelf registration process. Under this shelf process, Pioneer or Pioneer USA may sell any combination of the securities described in this prospectus in one or more offerings up to a total dollar amount of $1,000,000,000 or the equivalent denominated in foreign currencies. This prospectus provides you with a general description of the securities Pioneer or Pioneer USA may offer. Each time Pioneer or Pioneer USA sells securities, Pioneer or Pioneer USA will provide a prospectus supplement that will contain specific information about the terms of that offering. This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and any prospectus supplement together with additional information under the heading “Where You Can Find More Information.”

      You should rely only on the information contained or incorporated by reference in this prospectus and any prospectus supplement. Pioneer and Pioneer USA have not authorized anyone to provide you with different information. Pioneer and Pioneer USA are not making offers to sell the securities in any jurisdiction in which an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation.

      The information in this prospectus is accurate as of the date on the front cover. You should not assume that the information contained in this prospectus is accurate as of any other date.

      In this prospectus, references to the terms “we,” “us” or “Pioneer” or other similar terms refer to Pioneer Natural Resources Company, and not to Pioneer Natural Resources USA, Inc., unless we state otherwise or the context indicates otherwise. References to “Pioneer USA” refer to Pioneer Natural Resources USA, Inc.

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UNCERTAINTY OF FORWARD-LOOKING STATEMENTS

      This prospectus and the documents Pioneer and Pioneer USA incorporate by reference contain statements that constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, Section 21E of the Securities Exchange Act of 1934 and the Private Securities Litigation Reform Act of 1995. The forward-looking statements speak only as of the date made, and Pioneer and Pioneer USA undertake no obligation to update such forward-looking statements. These forward-looking statements may be identified by the use of the words “believe,” “expect,” “anticipate,” “will,” “contemplate,” “would” and similar expressions that contemplate future events. All statements other than statements of historical fact included or incorporated in this prospectus, including statements regarding Pioneer’s or Pioneer USA’s financial position, business strategy, production and reserve growth and other plans and objectives for Pioneer’s or Pioneer USA’s future operations, are forward-looking statements.

      Although Pioneer and Pioneer USA believe that such forward-looking statements are based on reasonable assumptions, Pioneer and Pioneer USA give no assurance that Pioneer’s or Pioneer USA’s expectations will in fact occur. Important factors could cause actual results to differ materially from those in the forward-looking statements, including factors identified in Pioneer’s periodic reports incorporated in this prospectus by reference. Forward-looking statements are subject to risks and uncertainties and include information concerning general economic conditions and possible or assumed future results of operations, estimates of oil and gas production and reserves, drilling plans, future cash flows, anticipated capital expenditures, Pioneer’s realization of deferred tax assets, the level of future expenditures for environmental costs, and the strategies, plans and objectives of Pioneer’s management.

      This cautionary statement expressly qualifies in their entirety all forward-looking statements attributable to Pioneer or Pioneer USA.

WHERE YOU CAN FIND MORE INFORMATION

      Pioneer files annual, quarterly and special reports, proxy statements and other information with the Securities and Exchange Commission. Pioneer’s SEC filings are available to the public over the internet at the SEC’s web site at http://www.sec.gov. You may also read and copy any document Pioneer files at the SEC’s public reference room at 450 Fifth Street, N.W., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the public reference room.

      Pioneer’s common stock is listed on the New York Stock Exchange and the Toronto Stock Exchange under the symbol “PXD.” Pioneer’s reports and other information filed with the SEC can also be inspected at the offices of the New York Stock Exchange and the Toronto Stock Exchange.

INFORMATION THAT PIONEER AND PIONEER USA INCORPORATE BY REFERENCE

      The SEC allows Pioneer and Pioneer USA to incorporate by reference the information Pioneer files with the SEC, which means that Pioneer and Pioneer USA can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus, and information Pioneer files later with the SEC will automatically update and supersede this information. Pioneer and Pioneer USA incorporate by reference the documents listed below that Pioneer filed with the SEC under the Securities Exchange Act of 1934:

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      Pioneer and Pioneer USA also incorporate by reference each of the documents that Pioneer files with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934 after the date of this prospectus until the offering of the securities terminates or Pioneer or Pioneer USA has filed with the SEC an amendment to the registration statement relating to this offering which deregisters all securities then remaining unsold.

      You may request a copy of any of these filings, other than an exhibit to those filings unless Pioneer or Pioneer USA has specifically incorporated that exhibit by reference into the filing, at no cost, by telephoning or writing Pioneer or Pioneer USA at the following address:

PIONEER AND PIONEER USA

      Pioneer is an oil and gas exploration and production company with ownership interests in oil and gas properties located in the United States, Argentina, Canada, Gabon, South Africa and Tunisia. Pioneer USA is a direct wholly-owned subsidiary of Pioneer and owns almost all of Pioneer’s United States oil and gas properties.

      The executive offices of Pioneer and Pioneer USA are located at 5205 N. O’Connor Blvd., Suite 1400, Irving, Texas 75039, telephone number: (972) 444-9001. Pioneer maintains other offices in Midland, Texas; Buenos Aires, Argentina; Calgary, Canada; and Capetown, South Africa.

USE OF PROCEEDS

      Unless Pioneer or Pioneer USA informs you otherwise in the prospectus supplement, each of Pioneer and Pioneer USA expect to use the net proceeds from the sale of securities for general corporate purposes. These purposes may include, but are not limited to:

      Pending any specific application, each of Pioneer and Pioneer USA may initially invest funds in short-term marketable securities or apply them to the reduction of short-term indebtedness.

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RATIOS OF EARNINGS TO FIXED CHARGES AND

      The following table sets forth Pioneer’s ratios of consolidated earnings to fixed charges and earnings to fixed charges and preferred stock dividends for the periods presented:

DESCRIPTION OF DEBT SECURITIES

      This section describes the general terms and provisions of the debt securities that Pioneer may issue separately, upon exercise of a debt warrant, in connection with a stock purchase contract or as part of a stock purchase unit from time to time in the form of one or more series of debt securities. The applicable prospectus supplement will describe the specific terms of the debt securities offered through that prospectus supplement as well as any general terms described in this section that will not apply to those debt securities.

      Pioneer’s senior debt securities will be issued under (1) an Indenture dated as of January 13, 1998, as supplemented, between Pioneer and The Bank of New York, as trustee, or (2) another indenture to be entered into by Pioneer and that or another trustee. Pioneer’s senior subordinated debt securities will be issued under a separate indenture to be entered into by Pioneer and that or another trustee. Under the indentures, Pioneer’s debt securities may be subordinated to other indebtedness of Pioneer. See “Description of Debt Securities — Subordination of Subordinated Debt Securities” below.

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      A copy of Pioneer’s 1998 senior debt indenture has been previously filed with the SEC and incorporated by reference as an exhibit to the registration statement of which this prospectus is a part, and is incorporated by reference into this prospectus. Another form of senior debt indenture is filed as an exhibit to the registration statement of which this prospectus is a part and is incorporated by reference into this prospectus. A form of the senior subordinated debt indenture is filed as an exhibit to the registration statement of which this prospectus is a part and is incorporated by reference into this prospectus. You should refer to the applicable indenture for more specific information. In addition, you should consult the applicable prospectus supplement for particular terms of Pioneer’s debt securities.

      The indentures will not limit the amount of debt securities that Pioneer may issue, and will permit Pioneer to issue securities from time to time in one or more series. The debt securities will be unsecured obligations of Pioneer, unless otherwise stated in the applicable prospectus supplement. Pioneer currently conducts substantially all of its operations through subsidiaries, and the holders of debt securities (whether senior or subordinated debt securities) will be effectively subordinated to the creditors of Pioneer’s subsidiaries. This means that creditors of Pioneer’s subsidiaries will have a claim to the assets of Pioneer’s subsidiaries that is superior to the claim of Pioneer’s creditors, including holders of Pioneer’s debt securities.

      Generally, Pioneer will pay the principal of, premium, if any, and interest on Pioneer’s registered debt securities either at an office or agency that Pioneer maintains for that purpose or, if Pioneer elects, Pioneer may pay interest by mailing a check to your address as it appears on Pioneer’s register (or, at the election of the holder, by wire transfer to an account designated by the holder). Except as may be provided otherwise in the applicable prospectus supplement, no payment on a bearer security will be made by mail to an address in the United States or by wire transfer to an account in the United States. Except as may be provided otherwise in the applicable prospectus supplement, Pioneer will issue its debt securities only in fully registered form without coupons, generally in denominations of $1,000 or integral multiples of $1,000. Pioneer will not apply a service charge for a transfer or exchange of its debt securities, but Pioneer may require that you pay the amount of any applicable tax or other governmental charge.

      The applicable prospectus supplement will describe the following terms of any series of debt securities that Pioneer may offer:

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      Debt securities may bear interest at fixed or floating rates. Pioneer may issue its debt securities at an original issue discount, bearing no interest or bearing interest at a rate that, at the time of issuance, is below market rate, to be sold at a substantial discount below their stated principal amount. Generally speaking, if Pioneer’s debt securities are issued at an original issue discount and there is an event of default or acceleration of their maturity, holders will receive an amount less than their principal amount. Tax and other special considerations applicable to any series of debt securities, including original issue discount debt, will be described in the prospectus supplement in which Pioneer offers those debt securities.

      Pioneer will have the ability under the indentures to reopen a previously issued series of debt securities and issue additional debt securities of that series or establish additional terms of the series. Pioneer is also permitted to issue debt securities with the same terms as previously issued debt securities.

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      Pioneer will comply with Section 14(e) under the Securities Exchange Act of 1934 and any other tender offer rules under the Securities Exchange Act of 1934 that may then apply to any obligation Pioneer may have to purchase debt securities at the option of the holders. Any such obligation applicable to a series of debt securities will be described in the related prospectus supplement.

Subordination of Subordinated Debt Securities

      Debt securities of a series may be subordinated to senior indebtedness to the extent set forth in the prospectus supplement relating to the subordinated debt securities. The definition of “senior indebtedness” (1) will include, among other things, Pioneer’s indebtedness, whether outstanding on the original issue date of the debt securities or incurred after such date, unless the instrument that creates or evidences such indebtedness provides that such obligations are subordinate in right of payment to the debt securities, and (2) will be specifically set forth in the prospectus supplement relating to the subordinated debt securities.

      Subordinated debt securities of a particular series and any coupons relating to those debt securities will be subordinate in right of payment, to the extent and in the manner set forth in the indenture and the prospectus supplement relating to those subordinated debt securities, to the prior payment of all of Pioneer’s indebtedness that is designated as senior indebtedness with respect to that series.

      Upon any payment or distribution of Pioneer’s assets to creditors or upon a total or partial liquidation or dissolution of Pioneer or in a bankruptcy, receivership, or similar proceeding relating to Pioneer or its property, holders of senior indebtedness will be entitled to receive payment in full in cash of the senior indebtedness before holders of subordinated debt securities will be entitled to receive any payment of principal, premium, if any, or interest with respect to the subordinated debt securities and, until the senior indebtedness is paid in full, any distribution to which holders of subordinated debt securities would otherwise be entitled will be made to the holders of senior indebtedness (except that holders of subordinated debt securities may receive shares of stock and any debt securities that are subordinated to senior indebtedness to at least the same extent as the subordinated debt securities), all as described in the applicable prospectus supplement.

      Unless otherwise provided in an applicable prospectus supplement, Pioneer may not (1) make any payments of principal, premium, if any, or interest with respect to subordinated debt securities, (2) make any deposit for the purpose of defeasance of the subordinated debt securities, or (3) repurchase, redeem, or otherwise retire (except, in the case of subordinated debt securities that provide for a mandatory sinking fund, by Pioneer’s delivery of subordinated debt securities to the trustee in satisfaction of Pioneer’s sinking fund obligation) any subordinated debt securities if:

unless, in either case, the default has been cured or waived and the acceleration has been rescinded, the senior indebtedness has been paid in full in cash, or Pioneer and the trustee receive written notice approving the payment from the representatives of each issue of specified senior indebtedness as described in the applicable prospectus supplement.

      Unless otherwise provided in an applicable prospectus supplement, during the continuance of any default (other than a default described in the preceding paragraph) with respect to any senior indebtedness pursuant to which the maturity of that senior indebtedness may be accelerated immediately without further notice (except such notice as may be required to effect the acceleration) or the expiration of any applicable grace periods, Pioneer may not pay the subordinated debt securities for such periods after notice of the default from the representative of specified senior indebtedness as shall be specified in the applicable prospectus supplement.

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      By reason of this subordination, in the event of insolvency, Pioneer’s creditors who are holders of senior indebtedness or holders of any indebtedness or preferred stock of Pioneer’s subsidiaries, as well as certain of Pioneer’s general creditors, may recover more, ratably, than the holders of the subordinated debt securities.

Events of Default

      Except as may be provided otherwise in a prospectus supplement, any of the following events will constitute an event of default for a series of debt securities under an indenture:

      An event of default with respect to one series of debt securities is not necessarily an event of default for another series.

      If there is an event of default with respect to a series of Pioneer’s debt securities, which continues for the requisite amount of time, either the trustee or holders of at least 25% of the aggregate principal amount of that series may declare the principal amount of and interest on all of the debt securities of that series to be due and payable immediately, except that if an event of default occurs due to bankruptcy, insolvency or reorganization as provided in the applicable indenture, then the principal of and interest on the debt securities shall become due and payable immediately without any act by the trustee or any holder of debt securities. If the securities were issued at an original issue discount, less than the stated principal amount may become payable.

      Before the acceleration of the maturity of the debt securities of any series, the holders of a majority in aggregate principal amount of the debt securities of that series may, on behalf of the holders of all debt securities and any related coupons of that series, waive any past default or event of default and its consequences for that series, except (1) a default in the payment of the principal, premium, or interest with respect to those debt securities or (2) a default with respect to a provision of the applicable indenture that cannot be amended without the consent of each holder affected by the amendment. In case of a waiver of a default, that default shall cease to exist, any event of default arising from that default shall be deemed to have been cured for all purposes, and Pioneer, the trustee, and the holders of the senior debt securities of that series will be restored to their former positions and rights under the indenture.

      The trustee under an indenture will, within 90 days after the occurrence of a default known to it with respect to a series of debt securities, give to the holders of the debt securities of that series notice of all

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      A holder may institute a suit against Pioneer for enforcement of such holder’s rights under the applicable indenture, for the appointment of a receiver or trustee, or for any other remedy only if the following conditions are satisfied:

      The indentures will require Pioneer every year to deliver to the trustee a statement as to performance of Pioneer’s obligations under the indentures and as to any defaults.

      A default in the payment of any of Pioneer’s debt securities, or a default with respect to Pioneer’s debt securities that causes them to be accelerated, may give rise to a cross-default under Pioneer’s bank credit facility or other indebtedness.

Satisfaction and Discharge of the Indentures

      An indenture will generally cease to be of any further effect with respect to a series of debt securities if:

and if, in either case, Pioneer also pays or causes to be paid all other sums payable under the applicable indenture by Pioneer.

Legal Defeasance and Covenant Defeasance

      Any series of Pioneer’s debt securities may be subject to the defeasance and discharge provisions of the applicable indenture if so specified in the applicable prospectus supplement. If those provisions are applicable, Pioneer may elect either:

      If Pioneer exercises its legal defeasance option with respect to a series of debt securities, payment of those debt securities may not be accelerated because of an event of default. If Pioneer exercise its

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      Unless otherwise provided in the applicable prospectus supplement, Pioneer may invoke legal defeasance or covenant defeasance with respect to any series of its debt securities only if:

Modification and Waiver

      Pioneer may enter into supplemental indentures for the purpose of modifying or amending an indenture with the consent of holders of at least a majority in aggregate principal amount of each series of Pioneer’s outstanding debt securities affected. However, unless otherwise provided in the applicable prospectus supplement, the consent of all of the holders of Pioneer’s debt securities that are affected by any modification or amendment is required for any of the following:

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      In addition, Pioneer and the trustee with respect to an indenture may enter into supplemental indentures without the consent of the holders of debt securities for one or more of the following purposes (in addition to any other purposes specified in an applicable prospectus supplement):

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Consolidation, Merger and Sale of Assets

      Unless otherwise provided in the applicable prospectus supplement, the indentures prohibit Pioneer from consolidating with or merging into another business entity, or transferring or leasing substantially all of Pioneer’s assets, unless:

Conversion or Exchange Rights

      If debt securities of any series are convertible or exchangeable, the applicable prospectus supplement will specify:

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Global Securities

      Pioneer’s debt securities may be issued in the form of one or more global securities that will be deposited with a depositary or its nominee identified in the applicable prospectus supplement. If so, each global security will be issued in the denomination of the aggregate principal amount of securities that it represents. Unless and until it is exchanged in whole or in part for debt securities that are in definitive registered form, a global security may not be transferred or exchanged except as a whole to the depositary, another nominee of the depositary, or a successor of the depositary or its nominee. The applicable prospectus supplement will describe this concept more fully.

      The specific material terms of the depositary arrangement with respect to any portion of a series of Pioneer’s debt securities that will be represented by a global security will be described in the applicable prospectus supplement. Pioneer anticipates that the following provisions will apply to Pioneer’s depositary arrangements.

      Upon the issuance of any global security, and its deposit with or on behalf of the depositary, the depositary will credit, on its book-entry registration and transfer system, the principal amounts of Pioneer’s debt securities represented by the global security to the accounts of participating institutions that have accounts with the depositary or its nominee. The underwriters or agents engaging in the distribution of Pioneer’s debt securities, or Pioneer, if Pioneer is offering and selling its debt securities directly, will designate the accounts to be credited. Ownership of beneficial interests in a global security will be limited to participating institutions or their clients. The depositary or its nominee will keep records of the ownership and transfer of beneficial interests in a global security by participating institutions. Participating institutions will keep records of the ownership and transfer of beneficial interests by their clients. The laws of some jurisdictions may require that purchasers of Pioneer’s securities receive physical certificates, which may impair a holder’s ability to transfer its beneficial interests in global securities.

      While the depositary or its nominee is the registered owner of a global security, the depositary or its nominee will be considered the sole owner of all of Pioneer’s debt securities represented by the global security for all purposes under the indentures. Generally, if a holder owns beneficial interests in a global security, that holder will not be entitled to have Pioneer’s debt securities registered in that holder’s own name, and that holder will not be entitled to receive a certificate representing that holder’s ownership. Accordingly, if a holder owns a beneficial interest in a global security, the holder must rely on the depositary and, if applicable, the participating institution of which that holder is a client to exercise the rights of that holder under the applicable indenture.

      The depositary may grant proxies and otherwise authorize participating institutions to take any action that a holder is entitled to take under the indentures. Pioneer understands that, according to existing industry practices, if Pioneer requests any action of holders, or any owner of a beneficial interest in a global security wishes to give any notice or take any action, the depositary would authorize the participating institutions to give the notice or take the action, and the participating institutions would in turn authorize their clients to give the notice or take the action.

      Generally, Pioneer will make payments on its debt securities represented by a global security directly to the depositary or its nominee. It is Pioneer’s understanding that the depositary will then credit the accounts of participating institutions, which will then distribute funds to their clients. Pioneer also expects that payments by participating institutions to their clients will be governed by standing instructions and customary practices, as is now the case with securities held for the accounts of clients registered in “street names,” and will be the responsibility of the participating institutions. Neither Pioneer nor the trustee, nor their respective agents, will have any responsibility, or bear any liability, for any aspects of the records relating to or payments made on account of beneficial interests in a global security, or for maintaining, supervising or reviewing records relating to beneficial interests.

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      Generally, a global security may be exchanged for certificated debt securities only in the following instances:

      The following is based on information furnished to Pioneer:

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      DTC may discontinue providing its services as depositary with respect to any securities at any time by giving reasonable notice to the issuer of such securities. If a successor depositary is not obtained, individual security certificates representing such securities are required to be printed and delivered. Pioneer, at its option, may decide to discontinue use of the system of book-entry transfers through DTC or a successor depositary.

      The information in this section concerning DTC and DTC’s book-entry system has been obtained from sources that Pioneer believes to be accurate, but Pioneer assumes no responsibility for its accuracy. Pioneer has no responsibility for the performance by DTC or its participants of their obligations as described in this prospectus or under the rules and procedures governing their operations.

      Debt securities may be issued as registered securities (which will be registered as to principal and interest in the register maintained by the registrar for those senior debt securities) or bearer securities (which will be transferable only by delivery). If debt securities are issuable as bearer securities, certain special limitations and considerations will apply, as set forth in the applicable prospectus supplement.

Pioneer’s Trustee

      The current trustee for Pioneer’s debt securities issued under its 1998 indenture is The Bank of New York. Pioneer may engage additional or substitute trustees with respect to particular series of Pioneer’s debt securities. Pioneer or Pioneer USA may maintain banking and other commercial relationships with any trustee, including The Bank of New York, and its affiliates in the ordinary course of business. A trustee may own Pioneer’s debt securities.

Governing Law

      The indentures and the debt securities are governed by the laws of the State of New York.

DESCRIPTION OF CAPITAL STOCK

      Pioneer authorized capital stock consists of 600,000,000 shares of stock, including:

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      In addition, Pioneer Natural Resources Canada Inc., an indirect wholly-owned subsidiary of Pioneer that we call Pioneer Canada, has 940,790 exchangeable shares issued and outstanding as of May 14, 2002, each of which is exchangeable into Pioneer’s common stock.

Common Stock

      This section describes the general terms of Pioneer’s common stock. For more detailed information, you should refer to Pioneer’s amended and restated certificate of incorporation and amended and restated bylaws, copies of which have been filed with the SEC. These documents are also incorporated by reference into this prospectus.

      Holders of Pioneer’s common stock are entitled to one vote per share with respect to each matter submitted to a vote of Pioneer’s stockholders, subject to voting rights that may be established for shares of Pioneer’s preferred stock, if any. Except as may be provided in connection with Pioneer’s preferred stock (such as the special preferred voting stock) or as otherwise may be required by law or Pioneer’s amended and restated certificate of incorporation, Pioneer’s common stock is the only capital stock entitled to vote in the election of directors. Pioneer’s common stock does not have cumulative voting rights.

      Subject to the rights of holders of Pioneer’s preferred stock, if any, holders of Pioneer’s common stock are entitled to receive dividends and distributions lawfully declared by Pioneer’s board of directors. If Pioneer liquidates, dissolves, or winds up its business, whether voluntarily or involuntarily, holders of Pioneer’s common stock will be entitled to receive any assets available for distribution to Pioneer’s stockholders after Pioneer has paid or set apart for payment the amounts necessary to satisfy any preferential or participating rights to which the holders of each outstanding series of preferred stock are entitled by the express terms of such series of preferred stock.

      The outstanding shares of Pioneer’s common stock are fully paid and nonassessable. Pioneer’s common stock does not have any preemptive, subscription or conversion rights. Pioneer may issue additional shares of its authorized common stock as it is authorized by its board of directors from time to time, without stockholder approval, except as may be required by applicable stock exchange requirements.

Preferred Stock

      This section describes the general terms and provisions of Pioneer’s preferred stock. The applicable prospectus supplement will describe the specific terms of the shares of preferred stock offered through that prospectus supplement, as well as any general terms described in this section that will not apply to those shares of preferred stock. Pioneer will file a copy of the certificate of designations that contains the terms of each new series of preferred stock with the SEC each time Pioneer issues a new series of preferred stock. Each certificate of designations will establish the number of shares included in a designated series and fix the designation, powers, privileges, preferences and rights of the shares of each series as well as any applicable qualifications, limitations or restrictions. You should refer to the applicable certificate of designations as well as Pioneer’s amended and restated certificate of incorporation before deciding to buy shares of Pioneer’s preferred stock as described in the applicable prospectus supplement.

      Pioneer’s board of directors has been authorized to provide for the issuance of shares of Pioneer’s preferred stock in multiple series without the approval of stockholders. With respect to each series of Pioneer’s preferred stock, Pioneer’s board of directors has the authority to fix the following terms:

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      Your rights with respect to your shares of preferred stock will be subordinate to the rights of Pioneer’s general creditors. Shares of Pioneer’s preferred stock that Pioneer issues will be fully paid and nonassessable, and will not be entitled to preemptive rights unless specified in the applicable prospectus supplement.

      Pioneer’s ability to issue preferred stock, or rights to purchase such shares, could discourage an unsolicited acquisition proposal. For example, Pioneer could impede a business combination by issuing a series of preferred stock containing class voting rights that would enable the holders of such preferred stock to block a business combination transaction. Alternatively, Pioneer could facilitate a business combination transaction by issuing a series of preferred stock having sufficient voting rights to provide a required percentage vote of the stockholders. Additionally, under certain circumstances, Pioneer’s issuance of preferred stock could adversely affect the voting power of the holders of Pioneer’s common stock. Although Pioneer’s board of directors is required to make any determination to issue any preferred stock based on its judgment as to the best interests of Pioneer’s stockholders, Pioneer’s board of directors could act in a manner that would discourage an acquisition attempt or other transaction that some, or a majority, of Pioneer’s stockholders might believe to be in their best interests or in which stockholders might receive a premium for their stock over prevailing market prices of such stock. Pioneer’s board of directors does not at present intend to seek stockholder approval prior to any issuance of currently authorized stock, unless otherwise required by law or applicable stock exchange requirements.

      In connection with Pioneer’s December 1997 acquisition of Chauvco Resources Ltd., an Alberta, Canada corporation, Pioneer’s board of directors designated one share of the authorized shares of preferred stock as special preferred voting stock. Pioneer refers to that one share as the voting share. The Montreal Trust Company of Canada holds the voting share as trustee on behalf of the holders of exchangeable shares of Pioneer Canada. The certificate of designations for the voting share includes the following important terms:

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Rights Agreement

      Attached to each share of Pioneer’s common stock and each exchangeable share of Pioneer Canada is one preferred share purchase right. Each right entitles the registered holder to purchase from Pioneer one one-thousandth of a share of Series A Junior Participating Preferred Stock, par value $0.01, at a price of $95.00 per one one-thousandth of a share of Series A Junior Participating Preferred Stock, subject to adjustment. The rights expire on July 31, 2011, unless the final expiration date is extended or unless the rights are earlier redeemed by Pioneer.

      The rights represented by the certificates for Pioneer’s common stock are not exercisable, and are not separately transferable from the common stock, until the earlier of:

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      The earlier of these two dates is called the “distribution date.” Separate certificates for the rights will be mailed to holders of record of Pioneer’s common stock as of the distribution date. The rights could then begin trading separately from Pioneer’s common stock.

      Generally, in the event that a person or group becomes an acquiring person, each right, other than the rights owned by the acquiring person, will entitle the holder to receive, upon exercise of the right, common stock having a value equal to two times the exercise price of the right. In the event that Pioneer is acquired in a merger, consolidation, or other business combination transaction or more than 50% of Pioneer’s assets, cash flow or earning power is sold or transferred, each right, other than the rights owned by an acquiring person, will entitle the holder to receive, upon the exercise of the right, common stock of the surviving corporation having a value equal to two times the exercise price of the right.

      At any time after the acquisition by the acquiring person of beneficial ownership of 15% or more of the outstanding shares of Pioneer’s common stock and before the acquisition by the acquiring person of 50% or more of the voting power of the outstanding shares of Pioneer’s common stock, the board of directors may exchange the rights, other than rights owned by the acquiring person, which would have become void, in whole or in part, at an exchange ratio of one share of Pioneer’s common stock for each two shares of Pioneer’s common stock for which each right is then exercisable, subject to adjustment.

      The rights are redeemable in whole, but not in part, at $0.001 per right until any person or group becomes an acquiring person. The ability to exercise the rights terminates at the time that the board of directors elects to redeem the rights. Notice of redemption will be given by mail to the registered holders of the rights. At no time will the rights have any voting rights.

      The number of outstanding rights, the exercise price payable, and the number of shares of Series A Junior Participating Preferred Stock or other securities or property issuable upon exercise of the rights are subject to customary adjustments from time to time to prevent dilution.

      The rights have certain anti-takeover effects. The rights may cause substantial dilution to a person or group that attempts to acquire Pioneer on terms not approved by Pioneer’s board of directors, except in the case of an offer conditioned on a substantial number of rights being acquired. The rights should not interfere with any merger or other business combination that Pioneer’s board of directors approves.

      The shares of Series A Junior Participating Preferred Stock that may be purchased upon exercise of the right will rank junior to all other series of Pioneer’s preferred stock, if any, or any similar stock that specifically provides that it ranks prior to the shares of Series A Junior Participating Preferred Stock. The shares of Series A Junior Participating Preferred Stock will be nonredeemable. Each share of Series A Junior Participating Preferred Stock will be entitled to a minimum preferential quarterly dividend of $1.00 per share, if, as and when declared, but will be entitled to an aggregate dividend of 1,000 times the dividend declared per share of Pioneer’s common stock. In the event of liquidation, the holders of the shares of Series A Junior Participating Preferred Stock will be entitled to a minimum preferential liquidation payment of $1,000 per share, but will be entitled to an aggregate payment of 1,000 times the payment made per share of Pioneer’s common stock. Each share of Series A Junior Participating Preferred Stock will have 1,000 votes, voting together with Pioneer’s common stock. In the event of any merger, consolidation or other transaction in which Pioneer’s common stock is exchanged, each share of Series A Junior Participating Preferred Stock will be entitled to receive 1,000 times the amount and type of consideration received per share of Pioneer’s common stock. These rights are protected by customary anti-dilution provisions. Because of the nature of the Series A Junior Participating Preferred Stock’s dividend, liquidation and voting rights, the value of the interest in a share of Series A Junior Participating Preferred Stock purchasable upon the exercise of each right should approximate the value of one share of Pioneer’s common stock.

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      The description of the rights contained in this section does not describe every aspect of the rights. The rights agreement dated as of July 20, 2001, between Pioneer and the rights agent, contains the full legal text of the matters described in this section. A copy of the rights agreement has been incorporated by reference in the registration statement of which this prospectus forms a part. See “Where You Can Find More Information” for information on how to obtain a copy.

Limitation on Directors’ Liability

      Pioneer’s amended and restated certificate of incorporation provides, as authorized by Section 102(b)(7) of the Delaware General Corporation Law, that Pioneer’s directors will not be personally liable to Pioneer or its stockholders for monetary damages for breach of fiduciary duty as a director, except for liability:

      The inclusion of this provision in Pioneer’s amended and restated certificate of incorporation may have the effect of reducing the likelihood of derivative litigation against directors, and may discourage or deter stockholders or management from bringing a lawsuit against directors for breach of their duty of care, even though such an action, if successful, might otherwise have benefited Pioneer and its stockholders.

Section 203 of the Delaware General Corporation Law

      Section 203 of the Delaware General Corporation Law prohibits a defined set of transactions between a Delaware corporation, such as Pioneer, and an “interested stockholder.” An interested stockholder is defined as a person who, together with any affiliates or associates of such person, beneficially owns, directly or indirectly, 15% or more of the outstanding voting shares of a Delaware corporation. This provision may prohibit business combinations between an interested stockholder and a corporation for a period of three years after the date the interested stockholder becomes an interested stockholder. The term “business combination” is broadly defined to include mergers, consolidations, sales or other dispositions of assets having a total value in excess of 10% of the consolidated assets of the corporation, and some other transactions that would increase the interested stockholder’s proportionate share ownership in the corporation.

      This prohibition is effective unless:

Special Charter and Bylaw Provisions

      Pioneer’s amended and restated certificate of incorporation contains provisions requiring that advance notice be delivered to Pioneer of any business to be brought by a stockholder before an annual meeting of stockholders and providing for certain procedures to be followed by stockholders in nominating persons for election to Pioneer’s board of directors. Generally, such advance notice provisions provide that the

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      Pioneer’s amended and restated certificate of incorporation provides that stockholders may not act by written consent in lieu of a meeting. Special meetings of the stockholders may be called by Pioneer’s board of directors, but may not be called by Pioneer’s stockholders. Pioneer’s amended and restated bylaws may be amended by Pioneer’s board of directors or by the affirmative vote of the holders of at least 66 2/3% of the aggregate voting power of Pioneer’s outstanding capital stock entitled to vote in the election of directors.

      Pioneer’s amended and restated certificate of incorporation also contains a “fair price” provision that applies to certain business combination transactions involving any person or group that beneficially owns at least 10% of the aggregate voting power of Pioneer’s outstanding capital stock, referred to as a “related person.” The “fair price” provision requires the affirmative vote of the holders of:

      This voting requirement will not apply to certain transactions, including:

      This provision could have the effect of delaying or preventing change in control in a transaction or series of transactions that did not satisfy the “fair price” criteria.

      The provisions of Pioneer’s amended and restated certificate of incorporation relating to the limitation of actions taken by written consent, and the “fair price” provision may be amended only by the affirmative vote of the holders of at least 80% of the aggregate voting power of Pioneer’s outstanding capital stock entitled to vote for the election of directors.

      The foregoing provisions of Pioneer’s amended and restated certificate of incorporation and Pioneer’s amended and restated bylaws, together with the rights agreement and the provisions of Section 203 of the Delaware General Corporation Law, could have the effect of delaying, deferring or preventing a change in

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Transfer Agent and Registrar

      Continental Stock Transfer & Trust Company serves as the registrar and transfer agent for the common stock.

Stock Exchange Listing

      Pioneer’s common stock is listed on the New York Stock Exchange and the Toronto Stock Exchange. The trading symbol for Pioneer’s common stock on these exchanges is “PXD.”

Pioneer Canada Exchangeable Shares

      In connection with the acquisition of Chauvco Resources Ltd., Pioneer (1) issued the voting share to a share trustee for the benefit of the holders, other than Pioneer and its subsidiaries, of the exchangeable shares issued by Pioneer Canada, (2) entered into a support agreement and a voting and exchange trust agreement and (3) assumed specified obligations with respect to the exchangeable shares. The rights, privileges, restrictions and conditions attaching to the exchangeable shares may be changed only with the approval of the holders of the exchangeable shares. The exchangeable shares have the rights and preferences described below.

      Holders of exchangeable shares are entitled to receive dividends equal to dividends paid from time to time by Pioneer on shares of its common stock. The declaration date, record date and payment date for dividends on the exchangeable shares will be the same as that for the corresponding dividends on Pioneer’s common stock.

      The holders of the exchangeable shares are entitled to instruct the share trustee to vote with respect to any matter, proposition or question on which Pioneer’s common stockholders are entitled to vote.

      Optional Redemption — Subject to Pioneer’s exercise of its optional call right, as described below under the heading “Call Rights — Optional Call Right Instead of Optional Redemption,” each holder of exchangeable shares, at the holder’s option, may redeem each of the holder’s exchangeable shares for one share of Pioneer’s common stock plus any unpaid dividends on such exchangeable shares. Pioneer Canada, or, if it is unable to do so, Pioneer must pay the redemption price on the date specified by the holder, which date must be not less than three nor more than 10 business days after the redemption request.

      Automatic Redemption — Upon at least 120 days’ prior written notice by Pioneer Canada to the holders of exchangeable shares and subject to Pioneer’s exercise of its optional call right, as described below under the heading “Call Rights — Optional Call Right Instead of Automatic Redemption,” on the automatic redemption date, as defined below, Pioneer Canada will redeem each outstanding exchangeable share for one share of Pioneer’s common stock plus any unpaid dividends on such exchangeable shares. Automatic redemption date means December 18, 2003, unless (a) that date is extended by Pioneer Canada’s board of directors to a date not later than December 31, 2005, or (b) such date shall be accelerated to an earlier date, but no earlier than the third anniversary of the first issuance of exchangeable shares, by Pioneer Canada’s board of directors if at the time of acceleration less than 5% of the number of

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      Optional Exchange Right — Upon a proposed liquidation, dissolution or winding-up of Pioneer Canada and subject to Pioneer’s exercise of its optional call right, as described below under the heading “Call Rights — Liquidation Call Right Instead of Optional Exchange Right,” the share trustee, if instructed by a holder of exchangeable shares, has the right to require Pioneer Canada, or if it is unable to do so, Pioneer, to purchase each of such holder’s exchangeable shares in exchange for one share of Pioneer’s common stock plus any unpaid dividends on such exchangeable shares.

      Automatic Exchange Right — Upon the liquidation, dissolution or winding-up of Pioneer, the share trustee, on behalf of the holders of the exchangeable shares, has the right to automatically exchange each exchangeable share for one share of Pioneer’s common stock plus any unpaid dividends on such exchangeable shares.

      Liquidation Call Right Instead of Optional Exchange Right — In the event of a proposed liquidation, dissolution or winding-up of Pioneer Canada, Pioneer has the right to purchase all of the outstanding exchangeable shares from the holders of the exchangeable shares on the effective date of any such liquidation, dissolution or winding-up in exchange for shares of Pioneer’s common stock.

      Optional Call Right Instead of Automatic Redemption — Notwithstanding any proposed automatic redemption of the exchangeable shares by Pioneer Canada, as described above under the heading “Redemption — Automatic Redemption,” Pioneer has the overriding optional call right to purchase all of the outstanding exchangeable shares from the holders of the exchangeable shares on the automatic redemption date in exchange for shares of Pioneer’s common stock plus any unpaid dividends on the exchangeable shares.

      Optional Call Right Instead of Optional Redemption — A proposed optional redemption by Pioneer Canada in response to a holder’s request to redeem such holder’s exchangeable shares will be deemed to be an offer of such exchangeable shares to Pioneer. Pioneer has the overriding optional call right to purchase the exchangeable shares tendered by such holder on the requested redemption date in exchange for shares of Pioneer’s common stock plus any unpaid dividends on the exchangeable shares.

      If the holder revokes his redemption request, Pioneer will not purchase such holder’s exchangeable shares nor will Pioneer Canada redeem such shares. If the holder does not revoke his redemption request, on the redemption date Pioneer will acquire or Pioneer Canada will redeem, as the case may be, such exchangeable shares, in either case for one share of Pioneer’s common stock for each exchangeable share plus any unpaid dividends on such exchangeable shares.

      Effect of Call Right Exercise — If Pioneer exercises one or more of its call rights, it will directly issue shares of its common stock to holders of exchangeable shares and will become the holder of such exchangeable shares. Pioneer will not be entitled to exercise any voting rights attached to the exchangeable shares it so acquires. If Pioneer declines to exercise its call rights when applicable, it will be required, pursuant to the support agreement described below, to issue shares of its common stock to Pioneer Canada which will, in turn, transfer such stock to the holders of exchangeable shares in consideration for the return and cancellation of such exchangeable shares.

      Pioneer has agreed to ensure that all shares of its common stock to be delivered by it under the support agreement or on the exercise of the exchange rights under the voting and exchange trust agreement are duly registered, qualified or approved under applicable Canadian and United States securities laws, if required, so that such shares may be freely traded by the holder of such shares, other

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      Under the support agreement, Pioneer has agreed that:

DESCRIPTION OF DEPOSITARY SHARES

General

      Pioneer may offer fractional shares of preferred stock, rather than full shares of preferred stock. If Pioneer does so, Pioneer may issue receipts for depositary shares that each represent a fraction of a share of a particular series of preferred stock. The prospectus supplement will indicate that fraction. The shares of preferred stock represented by depositary shares will be deposited under a depositary agreement between Pioneer and a bank depositary. The phrase “bank depositary” means a bank or trust company that meets certain requirements and is selected by Pioneer. Each owner of a depositary share will be entitled to all the rights and preferences of the preferred stock represented by the depositary share. The depositary shares will be evidenced by depositary receipts issued pursuant to the depositary agreement. Depositary receipts will be distributed to those persons purchasing the fractional shares of preferred stock in accordance with the terms of the offering.

      Pioneer has summarized some common provisions of a depositary agreement and the related depositary receipts. The forms of the depositary agreement and the depositary receipts relating to any

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Dividends and Other Distributions

      If Pioneer pays a cash distribution or dividend on a series of preferred stock represented by depositary shares, the bank depositary will distribute such dividends to the record holders of such depositary shares. If the distributions are in property other than cash, the bank depositary will distribute the property to the record holders of the depositary shares. However, if the bank depositary determines that it is not feasible to make the distribution of property, the bank depositary may, with Pioneer’s approval, sell such property and distribute the net proceeds from such sale to the record holders of the depositary shares.

Redemption of Depositary Shares

      If Pioneer redeems a series of preferred stock represented by depositary shares, the bank depositary will redeem the depositary shares from the proceeds received by the bank depositary in connection with the redemption. The redemption price per depositary share will equal the applicable fraction of the redemption price per share of the preferred stock. If fewer than all the depositary shares are redeemed, the depositary shares to be redeemed will be selected by lot or pro rata as the bank depositary may determine.

Voting the Preferred Stock

      Upon receipt of notice of any meeting at which the holders of the preferred stock represented by depositary shares are entitled to vote, the bank depositary will mail the notice to the record holders of the depositary shares relating to such preferred stock. Each record holder of these depositary shares on the record date (which will be the same date as the record date for the preferred stock) may instruct the bank depositary as to how to vote the preferred stock represented by such holder’s depositary shares. The bank depositary will endeavor, insofar as practicable, to vote the amount of the preferred stock represented by such depositary shares in accordance with such instructions, and Pioneer will take all action which the bank depositary deems necessary in order to enable the bank depositary to do so. The bank depositary will abstain from voting shares of the preferred stock to the extent it does not receive specific instructions from the holders of depositary shares representing such preferred stock.

Amendment and Termination of the Depositary Agreement

      The form of depositary receipt evidencing the depositary shares and any provision of the depositary agreement may be amended by agreement between the bank depositary and Pioneer. However, any amendment that materially and adversely alters the rights of the holders of depositary shares will not be effective unless such amendment has been approved by the holders of at least a majority of the depositary shares then outstanding. The depositary agreement may be terminated by the bank depositary or Pioneer only if (1) all outstanding depositary shares have been redeemed or (2) there has been a final distribution in respect of the preferred stock in connection with any liquidation, dissolution or winding up of Pioneer and such distribution has been distributed to the holders of depositary shares.

Charges of Bank Depositary

      Pioneer will pay all transfer and other taxes and governmental charges arising solely from the existence of the depositary arrangements. Pioneer will pay charges of the bank depositary in connection with the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary shares will pay other transfer and other taxes and governmental charges and any other charges, including a fee for the withdrawal of shares of preferred stock upon surrender of depositary receipts, as are expressly provided in the depositary agreement to be payable by such holders.

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Withdrawal of Preferred Stock

      Except as may be provided otherwise in the applicable prospectus supplement, upon surrender of depositary receipts at the principal office of the bank depositary, subject to the terms of the depositary agreement, the owner of the depositary shares may demand delivery of the number of whole shares of preferred stock and all money and other property, if any, represented by those depositary shares. Partial shares of preferred stock will not be issued. If the depositary receipts delivered by the holder evidence a number of depositary shares in excess of the number of depositary shares representing the number of whole shares of preferred stock to be withdrawn, the bank depositary will deliver to such holder at the same time a new depositary receipt evidencing the excess number of depositary shares. Holders of preferred stock thus withdrawn may not thereafter deposit those shares under the depositary agreement or receive depositary receipts evidencing depositary shares therefor.

Miscellaneous

      The bank depositary will forward to holders of depositary shares all reports and communications from Pioneer that are delivered to the bank depositary and that Pioneer is required to furnish to the holders of the preferred stock.

      Neither the bank depositary nor Pioneer will be liable if Pioneer is prevented or delayed by law or any circumstance beyond its control in performing its obligations under the depositary agreement. The obligations of the bank depositary and Pioneer under the depositary agreement will be limited to performance in good faith of their respective duties under the depositary agreement, and Pioneer will not be obligated to prosecute or defend any legal proceeding in respect of any depositary shares or preferred stock unless satisfactory indemnity is furnished. Pioneer may rely upon written advice of counsel or accountants, or upon information provided by persons presenting preferred stock for deposit, holders of depositary shares or other persons believed to be competent and on documents believed to be genuine.

Resignation and Removal of Bank Depositary

      The bank depositary may resign at any time by delivering to Pioneer notice of its election to do so, and Pioneer may at any time remove the bank depositary. Any such resignation or removal will take effect upon the appointment of a successor bank depositary and its acceptance of such appointment. The successor bank depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company meeting the requirements of the depositary agreement.

DESCRIPTION OF WARRANTS

General Description of Warrants

      Pioneer may issue warrants for the purchase of debt securities, preferred stock or common stock. Warrants may be issued independently or together with other securities and may be attached to or separate from any offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between Pioneer and a bank or trust company, as warrant agent. The warrant agent will act solely as Pioneer’s agent in connection with the warrants and will not have any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants. A copy of the warrant agreement will be filed with the SEC in connection with the offering of warrants.

Debt Warrants

      The prospectus supplement relating to a particular issue of warrants to purchase debt securities will describe the terms of those warrants, including the following:

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Stock Warrants

      The prospectus supplement relating to a particular issue of warrants to purchase common stock or preferred stock will describe the terms of the common stock warrants and preferred stock warrants, including the following:

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Exercise of Warrants

      Each warrant will entitle the holder of the warrant to purchase at the exercise price set forth in the applicable prospectus supplement the principal amount of debt securities or shares of preferred stock or common stock being offered. Holders may exercise warrants at any time up to the close of business on the expiration date set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants are void. Holders may exercise warrants as set forth in the prospectus supplement relating to the warrants being offered.

      Until you exercise your warrants to purchase Pioneer’s debt securities, preferred stock, or common stock, you will not have any rights as a holder of Pioneer’s debt securities, preferred stock, or common stock, as the case may be, by virtue of your ownership of warrants.

DESCRIPTION OF STOCK PURCHASE CONTRACTS AND

      Pioneer may issue stock purchase contracts, including contracts obligating holders to purchase from Pioneer, and obligating Pioneer to sell to the holders, a specified number of shares of common stock or other securities at a future date or dates, which Pioneer refers to in this prospectus as “stock purchase contracts.” The price per share of the securities and the number of shares of the securities may be fixed at the time the stock purchase contracts are issued or may be determined by reference to a specific formula set forth in the stock purchase contracts. The stock purchase contracts may be issued separately or as part of units consisting of a stock purchase contract and debt securities, preferred securities, warrants or other securities or debt obligations of third parties, including U.S. treasury securities, securing the holders’ obligations to purchase the securities under the stock purchase contracts, which Pioneer refers to in this prospectus as “stock purchase units.” The stock purchase contracts may require holders to secure their obligations under the stock purchase contracts in a specified manner. The stock purchase contracts also may require Pioneer to make periodic payments to the holders of the stock purchase units or vice versa, and those payments may be unsecured or refunded on some basis.

      The stock purchase contracts, and, if applicable, collateral or depositary arrangements, relating to the stock purchase contracts or stock purchase units, will be filed with the SEC in connection with the offering of stock purchase contracts or stock purchase units. The prospectus supplement relating to a particular issue of stock purchase contracts or stock purchase units will describe the terms of those stock purchase contracts or stock purchase units, including the following:

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DESCRIPTION OF GUARANTEES OF DEBT SECURITIES

      Pioneer USA may issue guarantees of debt securities offered by Pioneer in any prospectus supplement. A copy of the guarantee will be filed with the SEC in connection with the offering of guarantees. Each guarantee will be issued under an indenture. The prospectus supplement relating to a particular issue of guarantees will describe the terms of those guarantees, including the following:

PLAN OF DISTRIBUTION

      Pioneer or Pioneer USA may sell the offered securities in and outside the United States (1) through underwriters or dealers, (2) directly to purchasers, including Pioneer’s affiliates and stockholders, in a rights offering, (3) through agents or (4) through a combination of any of these methods. The prospectus supplement will include the following information:

Sale through Underwriters or Dealers

      If underwriters are used in the sale, the underwriters will acquire the securities for their own account for resale to the public, either on a firm commitment basis or a best efforts basis. The underwriters may resell the securities from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Underwriters may offer securities to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more firms acting as underwriters. Unless Pioneer or Pioneer USA informs you otherwise in the prospectus supplement, the obligations of the underwriters to purchase the securities will be subject to certain conditions. The underwriters may change from time to time any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers.

      Pioneer may also make direct sales through subscription rights distributed to its existing stockholders on a pro rata basis, which may or may not be transferable. In any distribution of subscription rights to Pioneer’s stockholders, if all of the underlying securities are not subscribed for, Pioneer may then sell the

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      During and after an offering through underwriters, the underwriters may purchase and sell the securities in the open market. These transactions may include overallotment and stabilizing transactions and purchases to cover syndicate short positions created in connection with the offering. The underwriters may also impose a penalty bid, which means that selling concessions allowed to syndicate members or other broker-dealers for the offered securities sold for their account may be reclaimed by the syndicate if the offered securities are repurchased by the syndicate in stabilizing or covering transactions. These activities may stabilize, maintain or otherwise affect the market price of the offered securities, which may be higher than the price that might otherwise prevail in the open market. If commenced, the underwriters may discontinue these activities at any time.

      Some or all of the securities that Pioneer or Pioneer USA offers though this prospectus may be new issues of securities with no established trading market. Any underwriters to whom Pioneer or Pioneer USA sells its securities for public offering and sale may make a market in those securities, but they will not be obligated to do so and they may discontinue any market making at any time without notice. Accordingly, each of Pioneer and Pioneer USA cannot assure you of the liquidity of, or continued trading markets for, any securities that it offers.

      If dealers are used in the sale of securities, Pioneer or Pioneer USA will sell the securities to them as principals. The dealers may then resell those securities to the public at varying prices determined by the dealers at the time of resale. Pioneer or Pioneer USA will include in the prospectus supplement the names of the dealers and the terms of the transaction.

Direct Sales and Sales through Agents

      Pioneer or Pioneer USA may sell the securities directly. In this case, no underwriters or agents would be involved. Pioneer or Pioneer USA may also sell the securities through agents designated from time to time. In the prospectus supplement, Pioneer or Pioneer USA will name any agent involved in the offer or sale of the offered securities, and Pioneer or Pioneer USA will describe any commissions payable to the agent. Unless Pioneer or Pioneer USA informs you otherwise in the prospectus supplement, any agent will agree to use its reasonable best efforts to solicit purchases for the period of its appointment.

      Pioneer or Pioneer USA may sell the securities directly to institutional investors or others who may be deemed to be underwriters within the meaning of the Securities Act of 1933 with respect to any sale of those securities. Pioneer or Pioneer USA will describe the terms of any such sales in the prospectus supplement.

Remarketing Arrangements

      Offered securities may also be offered and sold, if so indicated in the applicable prospectus supplement, in connection with a remarketing upon their purchase, in accordance with a redemption or repayment pursuant to their terms, or otherwise, by one or more remarketing firms, acting as principals for their own accounts or as agents for Pioneer or Pioneer USA. Any remarketing firm will be identified and the terms of its agreements, if any, with Pioneer or Pioneer USA and its compensation will be described in the applicable prospectus supplement. Remarketing firms may be deemed to be underwriters, as that term is defined in the Securities Act of 1933, in connection with the securities remarketed.

Delayed Delivery Contracts

      If Pioneer or Pioneer USA so indicates in the prospectus supplement, Pioneer or Pioneer USA may authorize agents, underwriters or dealers to solicit offers from certain types of institutions to purchase securities from Pioneer or Pioneer USA at the public offering price under delayed delivery contracts. These contracts would provide for payment and delivery on a specified date in the future. The contracts

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General Information

      Pioneer or Pioneer USA may have agreements with the agents, dealers, underwriters and remarketing firms to indemnify them against certain civil liabilities, including liabilities under the Securities Act of 1933, or to contribute with respect to payments that the agents, dealers, underwriters or remarketing firms may be required to make. Agents, dealers, underwriters and remarketing firms may be customers of, engage in transactions with or perform services for Pioneer or Pioneer USA in the ordinary course of their businesses.

LEGAL MATTERS

      Except as set forth in the applicable prospectus supplement, Vinson & Elkins L.L.P., Dallas, Texas, will pass upon the validity of Pioneer’s debt securities, common stock, preferred stock, depositary shares, warrants, stock purchase contracts and stock purchase units and Pioneer USA’s guarantees of debt securities.

EXPERTS

      Ernst & Young LLP, independent auditors, have audited our consolidated financial statements included in our annual report on Form 10-K as of December 31, 2001 and 2000, and for each of the years in the three-year period ended December 31, 2001, as set forth in their report, which is incorporated by reference in this prospectus and the registration statement. Our financial statements are incorporated by reference in this prospectus and the registration statement in reliance upon Ernst & Young LLP’s report, given on their authority as experts in accounting and auditing.

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