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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 8-K


                             CURRENT REPORT PURSUANT
                          TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                          DATE OF REPORT: JULY 23, 2003
                        (Date of Earliest Event Reported)


                          LEXICON GENETICS INCORPORATED
             (Exact Name of Registrant as Specified in Its Charter)


                                                                                
       DELAWARE                               000-30111                                    76-0474169
(State or Other Jurisdiction            (Commission File Number)                          (IRS Employer
   of Incorporation)                                                                   Identification No.)



                          8800 TECHNOLOGY FOREST PLACE
                           THE WOODLANDS, TEXAS 77381
    (Address of Registrant's Principal Executive Offices, Including Zip Code)



                                 (281) 863-3000
              (Registrant's Telephone Number, Including Area Code)

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ITEM 5. OTHER EVENTS AND REGULATION FD DISCLOSURE

        On July 23, 2003, Lexicon Genetics Incorporated (the "Company") entered
into an Underwriting Agreement with Morgan Stanley & Co. Incorporated, UBS
Securities LLC, CIBC World Markets Corp. and Punk, Ziegel & Company, L.P. for
the public offering, issuance and sale of up to 10,000,000 shares of the
Company's common stock, par value $.001 per share, plus up to an additional
1,500,000 shares solely to cover over-allotments, if any. The Underwriting
Agreement is filed as Exhibit 1.1 to this report and is incorporated herein by
reference. On July 23, 2003, the Company issued a press release announcing the
offering. The press release is filed as Exhibit 99.1 to this report and is
incorporated herein by reference.

        Also filed as exhibits 99.2 and 99.3 to this report and incorporated
herein by reference are certain amendments modifying (i) the Company's Synthetic
Lease Financing Facility with First Security Bank, National Association, the
Lenders and Holders named therein, and Bank of America, N.A. and (ii) the Lease
Agreement dated as of May 23, 2002 between Lexicon Pharmaceuticals (New Jersey),
Inc. and Townsend Property Trust Limited Partnership, respectively.

ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS

        (c) Exhibits

            1.1   Underwriting Agreement dated as of July 23, 2003 among the
                  Company, Morgan Stanley & Co. Incorporated, UBS Securities
                  LLC, CIBC World Markets Corp. and Punk, Ziegel & Company, L.P.

            5.1   Opinion of Vinson & Elkins L.L.P.

            23.1  Consent of Vinson & Elkins L.L.P. (included in Exhibit 5.1).

            99.1  Press Release dated July 23, 2003.

            99.2  Amendments to Certain Operative Agreements dated as of
                  September 17, 2001, February 17, 2002, August 7, 2002 and
                  December 20, 2002, in each case between the Company, Wells
                  Fargo Bank Northwest, National Association, the various banks
                  and other lending institutions which are parties to the
                  Participation Agreement and Certain Other Operative Agreements
                  from time to time and Bank of America, N.A.

            99.3  First Amendment of Lease Agreement dated as of January 16,
                  2003 between Lexicon Pharmaceuticals (New Jersey), Inc. and
                  Townsend Property Trust Limited Partnership; Assignment and
                  Amendment Agreement dated as of May 20, 2003 between Townsend
                  Property Trust Limited Partnership, Hopewell Property, LLC,
                  Lexicon Pharmaceuticals (New Jersey), Inc., the Princeton
                  Bio-Technology Center Condominium Association, Inc. and the
                  Company; Amended and Restated Memorandum of Lease dated as of
                  May 20, 2003 between Hopewell Property, LLC, Lexicon
                  Pharmaceuticals (New Jersey), Inc., Townsend Property Trust
                  Limited Partnership and the Princeton Bio-Technology Center
                  Condominium Association, Inc.; Letter dated July 2, 2003 from
                  Hopewell Property, LLC to Lexicon Pharmaceuticals (New
                  Jersey), Inc.

                                   SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                     LEXICON GENETICS INCORPORATED

Date:  July 24, 2003                 By: /s/ Jeffrey L. Wade
                                         ------------------------------------
                                         Jeffrey L. Wade
                                         Executive Vice President and
                                         General Counsel


                                  EXHIBIT INDEX



          Exhibit
          Number                   Description
          ------                   -----------

            1.1   Underwriting Agreement dated as of July 23, 2003 among the
                  Company, Morgan Stanley & Co. Incorporated, UBS Securities
                  LLC, CIBC World Markets Corp. and Punk, Ziegel & Company, L.P.

            5.1   Opinion of Vinson & Elkins L.L.P.

            23.1  Consent of Vinson & Elkins L.L.P. (included in Exhibit 5.1).

            99.1  Press Release dated July 23, 2003.

            99.2  Amendments to Certain Operative Agreements dated as of
                  September 17, 2001, February 17, 2002, August 7, 2002 and
                  December 20, 2002, in each case between the Company, Wells
                  Fargo Bank Northwest, National Association, the various banks
                  and other lending institutions which are parties to the
                  Participation Agreement and Certain Other Operative Agreements
                  from time to time and Bank of America, N.A.

            99.3  First Amendment of Lease Agreement dated as of January 16,
                  2003 between Lexicon Pharmaceuticals (New Jersey), Inc. and
                  Townsend Property Trust Limited Partnership; Assignment and
                  Amendment Agreement dated as of May 20, 2003 between Townsend
                  Property Trust Limited Partnership, Hopewell Property, LLC,
                  Lexicon Pharmaceuticals (New Jersey), Inc., the Princeton
                  Bio-Technology Center Condominium Association, Inc. and the
                  Company; Amended and Restated Memorandum of Lease dated as of
                  May 20, 2003 between Hopewell Property, LLC, Lexicon
                  Pharmaceuticals (New Jersey), Inc., Townsend Property Trust
                  Limited Partnership and the Princeton Bio-Technology Center
                  Condominium Association, Inc.; Letter dated July 2, 2003 from
                  Hopewell Property, LLC to Lexicon Pharmaceuticals (New
                  Jersey), Inc.