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

                                  SCHEDULE 13G
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934

                               (Amendment No. __)*

                            BAYER AKTIENGESELLSCHAFT
                                (Name of Issuer)

                                 ORDINARY SHARES
                         (Title of Class of Securities)

                                    072730302
                                 (CUSIP Number)

                                December 31, 2002
              Date of Event Which Requires Filing of this Statement

Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

      | |   Rule 13d-1(b)

      |X|   Rule 13d-1(c)

      | |   Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



                                  SCHEDULE 13G

-------------------                                            -----------------
CUSIP NO. 072730302                                            PAGE 2 OF 7 PAGES
-------------------                                            -----------------

--------------------------------------------------------------------------------
1.    NAME OF REPORTING PERSONS.

      I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY).

      Allianz Aktiengesellschaft
      FEIN 98-0122343

--------------------------------------------------------------------------------
2.    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)

      (a)  | |
      (b)  | |
--------------------------------------------------------------------------------
3.    SEC USE ONLY


--------------------------------------------------------------------------------
4.    CITIZENSHIP OR PLACE OF ORGANIZATION

      Federal Republic of Germany
--------------------------------------------------------------------------------
               5.   SOLE VOTING POWER

                    45,113,388
NUMBER OF      -----------------------------------------------------------------
SHARES         6.   SHARED VOTING POWER
BENEFICIALLY
OWNED BY            - 0 -
EACH           -----------------------------------------------------------------
REPORTING      7.   SOLE DISPOSITIVE POWER
PERSON
WITH                45,113,388
               -----------------------------------------------------------------
               8.   SHARED DISPOSITIVE POWER

                    - 0 -
--------------------------------------------------------------------------------
9.    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

      45,113,388
--------------------------------------------------------------------------------
10.   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
      (SEE INSTRUCTIONS)

      Not applicable
--------------------------------------------------------------------------------
11.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

      6.2%
--------------------------------------------------------------------------------
12.   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

      CO
--------------------------------------------------------------------------------


ITEM 1

      (a).  NAME OF ISSUER:

            Bayer Aktiengesellschaft

      (b).  ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

            Bayerwerk, Gebaude W1, Kaiser-Wilhelm-Allee, 51368 Leverkusen,
            Federal Republic of Germany

ITEM 2.

      (a).  NAME OF PERSON FILING:

            Allianz Aktiengesellschaft

      (b).  ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:

            Allianz Aktiengesellschaft, Koniginstrasse 28, 80802 Munich, Federal
            Republic of Germany

      (c).  CITIZENSHIP:

            See Item 4 on page 2.

      (d).  TITLE OF CLASS OF SECURITIES:

            The title of the securities is ordinary shares, which may also
            include securities held in the form of American Depositary Receipts
            (the "Ordinary Shares").

      (e).  CUSIP NUMBER:

            072730302

ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO SECTIONS 240.13D-1(B) OR
        240.13D-2(B) OR (C), CHECK WHETHER THE PERSON FILING IS A:

      (a).  | |   Broker or dealer registered under Section 15 of the Act
                  (15 U.S.C. 78o).

      (b).  | |   Bank as defined in Section 3(a)(6) of the Act (15 U.S.C. 78c).



      (c).  | |   Insurance company as defined in Section 3(a)(19) of the Act
                  (15 U.S.C. 78c).

      (d).  | |   Investment company registered under Section 8 of the
                  Investment Company Act of 1940 (15 U.S.C. 80a-8).

      (e).  | |   An investment advisor in accordance with Section
                  240.13d-1(b)(1)(ii)(E).

      (f).  | |   An employee benefit plan or endowment fund in accordance with
                  Section 240.13d-1(b)(1)(ii)(F).

      (g).  | |   A parent holding company or control person in accordance with
                  Section 240.13d-1(b)(1)(ii)(G).

      (h).  | |   A savings association as defined in Section 3(b) of the
                  Federal Deposit Insurance Act (12 U.S.C. 1813).

      (i).  | |   A church plan that is excluded from the definition of an
                  investment company under Section 3(c)(14) of the Investment
                  Company Act of 1940 (15 U.S.C. 80a-3).

      (j).  | |   Group, in accordance with Section 240.13d-1(b)(1)(ii)(J).

ITEM 4. OWNERSHIP.

Provide the following information regarding the aggregate number and percentage
of the class of securities of the issuer identified in Item 1.

      (a)   Amount beneficially owned:

            See Item 9 on page 2.

      (b)   Percent of class:

            See Item 11 on page 2.

      (c)   Number of shares as to which the person has:

            (i)   Sole power to vote or direct the vote:

                  See Item 5 on page 2.

            (ii)  Shared power to vote or direct the vote:

                  See Item 6 on page 2.



            (iii) Sole power to dispose or direct the disposition of:

                  See Item 7 on page 2.

            (iv)  Shared power to dispose or to direct the disposition of:

                  See Item 8 on page 2.

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

If this statement is being filed to report the fact that as of the date hereof
the reporting person has ceased to be the beneficial owner of more than five
percent of the class of securities, check the following | |.

      Not applicable

ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

      Certain of the Ordinary Shares are held in a fiduciary capacity for third
parties. Allianz Aktiengesellschaft disclaims beneficial ownership of such
Ordinary Shares.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
        SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY OR CONTROL
        PERSON.

      Allianz Aktiengesellschaft and the following subsidiaries of Allianz
Aktiengesellschaft hold Ordinary Shares of Bayer Aktiengesellschaft: Allianz
Lebensversicherungs-AG and other Allianz Aktiengesellschaft subsidiaries, each
of which such other Allianz Aktiengesellschaft subsidiaries holds less than one
percent (1%) of the Ordinary Shares of Bayer Aktiengesellschaft.

ITEM 8. IDENTIFICATION AND CLASSIFICATION OF THE MEMBERS OF THE GROUP.

      Not applicable



ITEM 9. NOTICE OF DISSOLUTION OF GROUP.

      Not applicable

ITEM 10. CERTIFICATIONS.

      By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were not acquired and are not held for the
purpose of or with the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose or effect.



                                    SIGNATURE

After reasonable inquiry and to the best of our knowledge and belief, we certify
that the information set forth in this statement is true, complete and correct.

                                                    FEBRUARY 14, 2003
                                        ----------------------------------------
                                                          Date

                                               ALLIANZ AKTIENGESELLSCHAFT


                                                   /s/ Peter Hemeling
                                        ----------------------------------------
                                                        Signature


                                                   Dr. Peter Hemeling/
                                                        Prokurist
                                        ----------------------------------------
                                                       Name/Title


                                                 /s/ Matthias J. Seewald
                                        ----------------------------------------
                                                        Signature

                                                  Matthias J. Seewald/
                                                        Prokurist
                                        ----------------------------------------
                                                       Name/Title