<PAGE>


   As filed with the Securities and Exchange Commission on September 3, 2003

                                        Registration Statement No. 333-

================================================================================

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549
                    ----------------------------------------
                                    Form S-8
                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933

                       -----------------------------------

                       AMERICAN INTERNATIONAL GROUP, INC.
             (Exact name of registrant as specified in its charter)

          Delaware                                           13-2592361
 (State or other jurisdiction of                         (I.R.S. employer
 incorporation or organization)                          identification no.)


                    70 Pine Street, New York, New York 10270
         (Address, including zip code, of principal executive offices)

 American International Group, Inc. Amended and Restated 1999 Stock Option Plan
  American International Group, Inc. Amended and Restated 1996 Employee Stock
                                 Purchase Plan
                            (Full title of the plans)

                               Kathleen E. Shannon
                        Senior Vice President, Secretary
                           and Deputy General Counsel
                                 70 Pine Street
                            New York, New York 10270
                                 (212) 770-7000

            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                 -----------------------------------------------

<TABLE>
<CAPTION>
                                                  Proposed maximum   Proposed maximum       Amount of
    Title of securities      Amount to be          offering price    aggregate offering   registration fee
     to be registered       registered (1)(2)       per share (3)        price (3)             (3)
     ----------------       -----------------       -------------        ---------             ---



<S>                         <C>                   <C>                <C>                  <C>
Common Stock,                35,781,250 shares        $58.89           $2,107,157,813       $170,469.07
par value $2.50 per share
</TABLE>

1.    This Registration Statement includes up to 5,290,625 shares of Common
      Stock that may be reoffered and resold by certain persons who may be
      deemed "affiliates" of American International Group, Inc. for purposes of
      the registration requirements of the Securities Act of 1933, as amended.

2.    This registration statement also relates to an indeterminate number of
      additional shares of Common Stock that may be issued pursuant to
      anti-dilution and adjustment provisions of the above-referenced plans.

3.    Estimated solely for purposes of calculating the registration fee. This
      estimate has been computed in accordance with Rule 457(c) and (h)(1) and
      is calculated based upon the average of the high and low sales prices of
      the Common Stock of American International Group, Inc. on September 2,
      2003, as reported on the New York Stock Exchange Composite Tape.
<PAGE>
                          INCORPORATION OF INFORMATION

      Pursuant to General Instruction E to Form S-8, all the contents of
Registration Statements Nos. 333-39976 and 333-48639 are hereby incorporated by
reference into this Registration Statement.
<PAGE>
                                   SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of New York, State of New York, on this 3rd day of
September, 2003.

                                     AMERICAN INTERNATIONAL GROUP, INC.


                                     By: /s/ M.R. Greenberg
                                        ----------------------------------------
                                        Name: M.R. Greenberg
                                        Title: Chairman and Chief Executive
                                               Officer


      KNOW ALL MEN BY THESE PRESENTS: that each person whose signature appears
below constitutes and appoints M. R. Greenberg, Howard I. Smith and Martin J.
Sullivan, and each of them, as true and lawful attorneys-in-fact and agents with
full power of substitution and resubstitution, for him or her and in his or her
name, place and stead, in any and all capacities to sign any and all amendments
(including post-effective amendments) to this Registration Statement on Form
S-8, and to file the same, with all exhibits thereto, and other documents in
connection herewith, with the Securities and Exchange Commission, granting unto
said attorneys-in-fact and agents, and each of them, full power and authority to
do and perform each and every act and thing required and necessary to be done in
and about the foregoing as fully for all intents and purposes as he or she might
or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

      Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.
<TABLE>
<CAPTION>

       SIGNATURE                              TITLE                           DATE
<S>                         <C>                                          <C>
                              Chairman, Chief Executive Officer
  /s/ M.R. Greenberg                    and Director
-----------------------          (Principal Executive Officer)           September 3, 2003
    (M.R. Greenberg)


                                  Vice Chairman, Chief Financial
  /s/ Howard I. Smith       Officer, Chief Administrative Officer and
-----------------------       Director (Principal Financial Officer)     September 3, 2003
   (Howard I. Smith)


/s/ Michael J. Castelli           Vice President and Comptroller
-----------------------           (Principal Accounting Officer)         September 3, 2003
 (Michael J. Castelli)



-----------------------                    Director
 (M. Bernard Aidinoff)

</TABLE>
<PAGE>
<TABLE>
<CAPTION>

       SIGNATURE                              TITLE                           DATE
<S>                         <C>                                          <C>

    /s/ Pei-yuan Chia
--------------------------                   Director                    September 3, 2003
     (Pei-yuan Chia)


  /s/ Marshall A. Cohen
--------------------------                   Director                    September 3, 2003
   (Marshall A. Cohen)


/s/ Barber B. Conable, Jr.
--------------------------                   Director                    September 3, 2003
 (Barber B. Conable, Jr.)


 /s/ Martin S. Feldstein
--------------------------                   Director                    September 3, 2003
  (Martin S. Feldstein)



--------------------------                   Director
    (Ellen V. Futter)


    /s/ Carla A. Hills
--------------------------                   Director                    September 3, 2003
     (Carla A. Hills)


 /s/ Frank J. Hoenemeyer
--------------------------                   Director                    September 3, 2003
  (Frank J. Hoenemeyer)


 /s/ Richard C. Holbrooke
--------------------------                   Director                    September 3, 2003
  (Richard C. Holbrooke)


  /s/ Martin J. Sullivan
--------------------------                   Director                    September 3, 2003
   (Martin J. Sullivan)



--------------------------                   Director
    (Edmund S.W. Tse)


    /s/ Jay S. Wintrob
--------------------------                   Director                    September 3, 2003
     (Jay S. Wintrob)


   /s/ Frank G. Wisner
--------------------------                   Director                    September 3, 2003
    (Frank G. Wisner)


    /s/ Frank G. Zarb
--------------------------                   Director                    September 3, 2003
     (Frank G. Zarb)

</TABLE>
<PAGE>
                                  EXHIBIT INDEX
<TABLE>
<CAPTION>
EXHIBIT
NUMBER                  DESCRIPTION                                                        LOCATION
------                  -----------                                                        --------

<S>     <C>                                                      <C>
4.1     American International Group, Inc. Amended and
        and Restated 1999 Stock Option Plan.................     Filed as exhibit to American International Group, Inc.'s
                                                                 Definitive Proxy Statement dated April 4, 2003 (File No. 1-8787)
                                                                 and incorporated herein by reference.

4.2     American International Group, Inc. Amended and
        Restated 1996 Employee Stock Purchase Plan..........     Filed as exhibit to American International Group, Inc.'s
                                                                 Definitive Proxy Statement dated April 4, 2003 (File No. 1-8787)
                                                                 and incorporated herein by reference.

5       Validity Opinion of Kathleen E. Shannon, Senior
        Vice President and Deputy General Counsel of
        American International Group, Inc. .................     Filed as exhibit hereto.

15      Letter re unaudited interim financial information...     None.

23.1    Consent of PricewaterhouseCoopers LLP, independent
        accountants for American International Group, Inc. .     Filed as exhibit hereto.

23.2    Consent of Kathleen E. Shannon, Senior Vice
        President and Deputy General Counsel of
        American International Group, Inc. .................     Included in Exhibit 5.

24      Power of Attorney...................................     Included in signature pages to this Registration Statement.

</TABLE>
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{"company-data": {"conformed-name": "AMERICAN INTERNATIONAL GROUP INC", "cik": "0000005272", "assigned-sic": "6331", "irs-number": "132592361", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-108466", "film-number": "03879427"}, "business-address": {"street1": "70 PINE ST", "city": "NEW YORK", "state": "NY", "zip": "10270", "phone": "2127707000"}, "mail-address": {"street1": "70 PINE STREET", "city": "NEW YORK", "state": "NY", "zip": "10270"}, "former-company": {"former-conformed-name": "AMERICAN INTERNATIONAL ENTERPRISES INC", "date-changed": "19700507"}}
As filed with the Securities and Exchange Commission on September 3, 2003

                                        Registration Statement No. 333-

================================================================================

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549
                    ----------------------------------------
                                    Form S-8
                             REGISTRATION STATEMENT
                                    UNDER THE
                             SECURITIES ACT OF 1933

                       -----------------------------------

                       AMERICAN INTERNATIONAL GROUP, INC.
             (Exact name of registrant as specified in its charter)

          Delaware                                           13-2592361
 (State or other jurisdiction of                         (I.R.S. employer
 incorporation or organization)                          identification no.)

                    70 Pine Street, New York, New York 10270
         (Address, including zip code, of principal executive offices)

 American International Group, Inc. Amended and Restated 1999 Stock Option Plan
  American International Group, Inc. Amended and Restated 1996 Employee Stock
                                 Purchase Plan
                            (Full title of the plans)

                               Kathleen E. Shannon
                        Senior Vice President, Secretary
                           and Deputy General Counsel
                                 70 Pine Street
                            New York, New York 10270
                                 (212) 770-7000

            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                 -----------------------------------------------
Proposed maximum   Proposed maximum       Amount of
    Title of securities      Amount to be          offering price    aggregate offering   registration fee
     to be registered       registered (1)(2)       per share (3)        price (3)             (3)
     ----------------       -----------------       -------------        ---------             ---
Common Stock,                35,781,250 shares        $58.89           $2,107,157,813       $170,469.07
par value $2.50 per share
1.    This Registration Statement includes up to 5,290,625 shares of Common
      Stock that may be reoffered and resold by certain persons who may be
      deemed "affiliates" of American International Group, Inc. for purposes of
      the registration requirements of the Securities Act of 1933, as amended.

2.    This registration statement also relates to an indeterminate number of
      additional shares of Common Stock that may be issued pursuant to
      anti-dilution and adjustment provisions of the above-referenced plans.

3.    Estimated solely for purposes of calculating the registration fee. This
      estimate has been computed in accordance with Rule 457(c) and (h)(1) and
      is calculated based upon the average of the high and low sales prices of
      the Common Stock of American International Group, Inc. on September 2,
      2003, as reported on the New York Stock Exchange Composite Tape.
INCORPORATION OF INFORMATION

      Pursuant to General Instruction E to Form S-8, all the contents of
Registration Statements Nos. 333-39976 and 333-48639 are hereby incorporated by
reference into this Registration Statement.
SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of New York, State of New York, on this 3rd day of
September, 2003.

                                     AMERICAN INTERNATIONAL GROUP, INC.

                                     By: /s/ M.R. Greenberg
                                        ----------------------------------------
                                        Name: M.R. Greenberg
                                        Title: Chairman and Chief Executive
                                               Officer

      KNOW ALL MEN BY THESE PRESENTS: that each person whose signature appears
below constitutes and appoints M. R. Greenberg, Howard I. Smith and Martin J.
Sullivan, and each of them, as true and lawful attorneys-in-fact and agents with
full power of substitution and resubstitution, for him or her and in his or her
name, place and stead, in any and all capacities to sign any and all amendments
(including post-effective amendments) to this Registration Statement on Form
S-8, and to file the same, with all exhibits thereto, and other documents in
connection herewith, with the Securities and Exchange Commission, granting unto
said attorneys-in-fact and agents, and each of them, full power and authority to
do and perform each and every act and thing required and necessary to be done in
and about the foregoing as fully for all intents and purposes as he or she might
or could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents or any of them, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

      Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.
SIGNATURE                              TITLE                           DATE
Chairman, Chief Executive Officer
  /s/ M.R. Greenberg                    and Director
-----------------------          (Principal Executive Officer)           September 3, 2003
    (M.R. Greenberg)

                                  Vice Chairman, Chief Financial
  /s/ Howard I. Smith       Officer, Chief Administrative Officer and
-----------------------       Director (Principal Financial Officer)     September 3, 2003
   (Howard I. Smith)

/s/ Michael J. Castelli           Vice President and Comptroller
-----------------------           (Principal Accounting Officer)         September 3, 2003
 (Michael J. Castelli)

-----------------------                    Director
 (M. Bernard Aidinoff)
SIGNATURE                              TITLE                           DATE
/s/ Pei-yuan Chia
--------------------------                   Director                    September 3, 2003
     (Pei-yuan Chia)

  /s/ Marshall A. Cohen
--------------------------                   Director                    September 3, 2003
   (Marshall A. Cohen)

/s/ Barber B. Conable, Jr.
--------------------------                   Director                    September 3, 2003
 (Barber B. Conable, Jr.)

 /s/ Martin S. Feldstein
--------------------------                   Director                    September 3, 2003
  (Martin S. Feldstein)

--------------------------                   Director
    (Ellen V. Futter)

    /s/ Carla A. Hills
--------------------------                   Director                    September 3, 2003
     (Carla A. Hills)

 /s/ Frank J. Hoenemeyer
--------------------------                   Director                    September 3, 2003
  (Frank J. Hoenemeyer)

 /s/ Richard C. Holbrooke
--------------------------                   Director                    September 3, 2003
  (Richard C. Holbrooke)

  /s/ Martin J. Sullivan
--------------------------                   Director                    September 3, 2003
   (Martin J. Sullivan)

--------------------------                   Director
    (Edmund S.W. Tse)

    /s/ Jay S. Wintrob
--------------------------                   Director                    September 3, 2003
     (Jay S. Wintrob)

   /s/ Frank G. Wisner
--------------------------                   Director                    September 3, 2003
    (Frank G. Wisner)

    /s/ Frank G. Zarb
--------------------------                   Director                    September 3, 2003
     (Frank G. Zarb)
EXHIBIT INDEX
EXHIBIT
NUMBER                  DESCRIPTION                                                        LOCATION
------                  -----------                                                        --------
4.1     American International Group, Inc. Amended and
        and Restated 1999 Stock Option Plan.................     Filed as exhibit to American International Group, Inc.'s
                                                                 Definitive Proxy Statement dated April 4, 2003 (File No. 1-8787)
                                                                 and incorporated herein by reference.

4.2     American International Group, Inc. Amended and
        Restated 1996 Employee Stock Purchase Plan..........     Filed as exhibit to American International Group, Inc.'s
                                                                 Definitive Proxy Statement dated April 4, 2003 (File No. 1-8787)
                                                                 and incorporated herein by reference.

5       Validity Opinion of Kathleen E. Shannon, Senior
        Vice President and Deputy General Counsel of
        American International Group, Inc. .................     Filed as exhibit hereto.

15      Letter re unaudited interim financial information...     None.

23.1    Consent of PricewaterhouseCoopers LLP, independent
        accountants for American International Group, Inc. .     Filed as exhibit hereto.

23.2    Consent of Kathleen E. Shannon, Senior Vice
        President and Deputy General Counsel of
        American International Group, Inc. .................     Included in Exhibit 5.

24      Power of Attorney...................................     Included in signature pages to this Registration Statement.