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


                                  SCHEDULE 13D
                    Under the Securities Exchange Act of 1934

                                (Amendment No. 21)
                          21st Century Insurance Group

                                (Name of Issuer)

                        Common Stock, Without Par Value

                         (Title of Class of Securities)

                                   901272 20 3

                                 (CUSIP Number)

                              Kathleen E. Shannon
                          Vice President and Secretary
                       American International Group, Inc.
               70 Pine Street, New York, NY 10270 (212) 770-7000
            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

                                April 7, 2000
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box: [ ].

NOTE:  Six copies of this statement, including all exhibits, should be
filed with the Commission.  See Rule 13d-1(a) for other parties to whom
copies are to be sent.








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CUSIP NO. 901272 20 3


 (1)  NAME OF REPORTING PERSON/S.S. OR I.R.S.
      IDENTIFICATION NO. OF ABOVE PERSON

American International Group, Inc.
(I.R.S. Identification No. 13-2592361)

 (2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                              (a)  / /
                              (b)  / /

 (3)  SEC USE ONLY


 (4)  SOURCES OF FUNDS

            WC, OO

 (5)  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEMS 2(d) OR 2(e)
                                   / /

 (6)  CITIZENSHIP OR PLACE OF ORGANIZATION

      Incorporated in the State of Delaware

NUMBER OF               (7)  SOLE VOTING POWER
SHARES
BENEFICIALLY            (8)  SHARED VOTING POWER
OWNED BY                     53,445,620
EACH                    (9)  SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH            (10)  SHARED DISPOSITIVE POWER
                             53,445,620

(11)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                             53,445,620

(12)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
      CERTAIN SHARES
                                   / /

(13)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
      62.6%

(14)  TYPE OF REPORTING PERSON

      HC, CO


                                 -2-
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CUSIP NO. 901272 20 3



 (1)  NAME OF REPORTING PERSON/S.S. OR I.R.S.
      IDENTIFICATION NO. OF ABOVE PERSON

American Home Assurance Company
(I.R.S. Identification No. 13-5124990)

 (2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                              (a)  / /
                              (b)  / /

 (3)  SEC USE ONLY


 (4)  SOURCES OF FUNDS

            OO

 (5)  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEMS 2(d) OR 2(e)
                                   / /

 (6)  CITIZENSHIP OR PLACE OF ORGANIZATION

      Incorporated in the State of New York


NUMBER OF               (7)  SOLE VOTING POWER
SHARES
BENEFICIALLY            (8)  SHARED VOTING POWER
OWNED BY                       14,395,665
EACH                    (9)  SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH            (10)  SHARED DISPOSITIVE POWER
                               14,395,665

(11)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                              14,395,665

(12)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
      CERTAIN SHARES
                                   / /

(13)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

          16.9%

(14)  TYPE OF REPORTING PERSON

      IC, CO


                                 -3-
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CUSIP NO. 901272 20 3


 (1)  NAME OF REPORTING PERSON/S.S. OR I.R.S.
      IDENTIFICATION NO. OF ABOVE PERSON

Commerce & Industry Insurance Company
(I.R.S. Identification No. 31-1938623)

 (2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                              (a)  / /
                              (b)  / /

 (3)  SEC USE ONLY


 (4)  SOURCES OF FUNDS

            OO

 (5)  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEMS 2(d) OR 2(e)
                                   / /

 (6)  CITIZENSHIP OR PLACE OF ORGANIZATION

      Incorporated in the State of New York


NUMBER OF               (7)  SOLE VOTING POWER
SHARES
BENEFICIALLY            (8)  SHARED VOTING POWER
OWNED BY                        5,414,827
EACH                    (9)  SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH            (10)  SHARED DISPOSITIVE POWER
                                5,414,827

(11)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                                5,414,827

(12)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
      CERTAIN SHARES
                                   / /

(13)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

      6.3%

(14)  TYPE OF REPORTING PERSON

      IC, CO


                                 -4-



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CUSIP NO. 901272 20 3


 (1)  NAME OF REPORTING PERSON/S.S. OR I.R.S.
      IDENTIFICATION NO. OF ABOVE PERSON

New Hampshire Insurance Company
(I.R.S. Identification No. 02-0172170)

 (2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                              (a)  / /
                              (b)  / /

 (3)  SEC USE ONLY


 (4)  SOURCES OF FUNDS

            OO

 (5)  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEMS 2(d) OR 2(e)
                                   / /

 (6)  CITIZENSHIP OR PLACE OF ORGANIZATION

      Incorporated in the State of Pennsylvania


NUMBER OF               (7)  SOLE VOTING POWER
SHARES
BENEFICIALLY            (8)  SHARED VOTING POWER
OWNED BY                        5,414,827
EACH                    (9)  SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH            (10)  SHARED DISPOSITIVE POWER
                                5,414,827

(11)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                                5,414,827

(12)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
      CERTAIN SHARES
                                   / /

(13)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

      6.3%

(14)  TYPE OF REPORTING PERSON

      IC, CO


                                 -5-
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CUSIP NO. 901272 20 3


 (1)  NAME OF REPORTING PERSON/S.S. OR I.R.S.
      IDENTIFICATION NO. OF ABOVE PERSON

National Union Fire Insurance Company of Pittsburgh, Pa.
(I.R.S. Identification No. 25-0687550)

 (2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                              (a)  / /
                              (b)  / /

 (3)  SEC USE ONLY


 (4)  SOURCES OF FUNDS

            WC, OO

 (5)  CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
      TO ITEMS 2(d) OR 2(e)
                                   / /

 (6)  CITIZENSHIP OR PLACE OF ORGANIZATION

      Incorporated in the State of Pennsylvania


NUMBER OF               (7)  SOLE VOTING POWER
SHARES
BENEFICIALLY            (8)  SHARED VOTING POWER
OWNED BY                     28,220,301
EACH                    (9)  SOLE DISPOSITIVE POWER
REPORTING
PERSON WITH            (10)  SHARED DISPOSITIVE POWER
                             28,220,301

(11)  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                             28,220,301

(12)  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
      CERTAIN SHARES
                                   / /

(13)  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

      33.0%

(14)  TYPE OF REPORTING PERSON

      IC, CO


                                 -6-
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ITEM 1.  SECURITY AND ISSUER.

            This Amendment No. 21 amends and supplements Item 5 of the Statement
on Schedule 13D dated December 16, 1994, as amended and supplemented by
Amendment No. 1 to Schedule 13D dated March 23, 1995, Amendment No. 2 to
Schedule 13D dated January 20, 1998, Amendment No. 3 to Schedule 13D dated April
9, 1998, Amendment No. 4 to Schedule 13D dated May 12, 1998, Amendment No. 5 to
Schedule 13D dated June 4, 1998, Amendment No. 6 to Schedule 13D dated June 15,
1998, Amendment No. 7 to Schedule 13D dated June 25, 1998, Amendment No. 8 to
Schedule 13D dated July 14, 1998, Amendment No. 9 to Schedule 13D dated July 23,
1998, Amendment No. 10 to Schedule 13D dated July 27, 1998, Amendment No. 11 to
Schedule 13D dated August 10, 1998, Amendment No. 12 to Schedule 13D dated
August 19, 1998, Amendment No. 13 to Schedule 13D dated August 24, 1998,
Amendment No. 14 to Schedule 13D dated September 3, 1998, Amendment No. 15 to
Schedule 13D dated September 11, 1998, Amendment No. 16 to Schedule 13D filed on
November 10, 1998, Amendment No. 17 to Schedule 13D filed on December 16, 1998,
Amendment No. 18 to Schedule 13D filed on February 5, 1999, Amendment No. 19
to Schedule 13D filed on April 1, 1999 and Amendment No. 20 to Schedule 13D
filed on May 3, 1999 ("Schedule 13D") previously filed by American
International Group, Inc., a Delaware corporation ("AIG"), relating to the
common stock, without par value ("Common Stock"), of 21st Century Insurance
Group, a California corporation (the "Company"). The principal executive
offices of the Company are located at Suite 700, 6301 Owensmouth Avenue,
Woodland Hills, California 91367.

            Each capitalized term used in this Statement which is defined in the
Schedule 13D shall have the meaning ascribed thereto in the Schedule 13D.

ITEM 5.  INTEREST IN SECURITIES OF THE ISSUER

            (a) As a result of purchases by the Company of its Common Stock in
open market transactions, AIG's and each AIG Sub's percentage ownership
interest in the Company has increased as the number of shares of Common Stock
outstanding decreased in connection with such purchases.

            In addition, between May 3, 1999 and May 7, 1999 AIG, through
its subsidiary National Union, purchased 431,700 shares of Common Stock in open
market transactions effected on the New York Stock Exchange at prices ranging
from $17.8750 to $17.9375 per share as follows:

DATE SHARES PRICE - ---- ------ ----- May 3, 1999 62,600 17.9375 May 4, 1999 288,600 17.9375 May 5, 1999 10,600 17.9375 May 6, 1999 35,800 17.8750 May 6, 1999 21,800 17.9375 May 7, 1999 12,300 17.9375
National Union's and each other AIG Sub's current ownership interests in the Company and the Common Stock is set forth on the cover pages to this Amendment No. 21 to Schedule 13D. The ownership percentages appearing on such pages have been calculated based on the number of shares of Common Stock outstanding as of April 7, 2000 (85,326,290 shares) as reported by the Company in the Company's Proxy Statement on Schedule 14A dated April 20, 2000. -7- 8 (b). AIG and each AIG Sub share voting and dispositive power as to the securities owned by such AIG Sub. (c). AIG, American Home, Commerce & Industry, National Union, New Hampshire, SICO, The Starr Foundation and Starr, and, to the best of each of their knowledge, the Covered Persons, have not engaged in any transactions in the Common Stock since the filing of Amendment No. 20 to Schedule 13D, except for the purchase by National Union between May 3, 1999 and May 7, 1999 of 431,700 shares of Common Stock as described in (a) above. -8- 9 SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct. Dated: May 31, 2000 AMERICAN INTERNATIONAL GROUP, INC. By: /s/ Kathleen E. Shannon --------------------------------------- Kathleen E. Shannon, Vice President and Secretary AMERICAN HOME ASSURANCE COMPANY By: /s/ Edward E. Matthews --------------------------------------- Edward E. Matthews, Senior Vice President COMMERCE AND INDUSTRY INSURANCE COMPANY By: /s/ Edward E. Matthews --------------------------------------- Edward E. Matthews, Senior Vice President NATIONAL UNION FIRE INSURANCE COMPANY OF PITTSBURGH, PA. By: /s/ Edward E. Matthews --------------------------------------- Edward E. Matthews, Senior Vice President NEW HAMPSHIRE INSURANCE COMPANY By: /s/ Edward E. Matthews --------------------------------------- Edward E. Matthews, Vice President -9-