Exhibit 5.1

                                                                   July 19, 2006

American International Group, Inc.,
70 Pine Street,
New York, New York 10270.

Ladies and Gentlemen:

     In connection with the registration under the Securities Act of 1933 (the
"Act") of $1,000,000,000 principal amount of 6.25% Notes Due 2036 (the
"Securities") of American International Group, Inc., a Delaware corporation (the
"Company"), to be issued pursuant to the Indenture, dated as of July 15, 1989,
as supplemented by the First Supplemental Indenture, dated as of May 15, 2003,
the Second Supplemental Indenture, dated as of September 30, 2005 and the Third
Supplemental Indenture, dated as of April 20, 2006 (together, the "Indenture"),
between the Company and The Bank of New York, as Trustee (the "Trustee"), we, as
your counsel, have examined such corporate records, certificates and other
documents, and



American International Group, Inc.,                                          -2-


such questions of law, as we have considered necessary or appropriate for the
purposes of this opinion.

     Upon the basis of such examination, we advise you that, in our opinion,
when the Registration Statement has become effective under the Act, and the
Securities have been duly executed and authenticated in accordance with the
Indenture and issued and delivered in exchange for the Company's outstanding
6.25% Notes Due 2036 as contemplated by the Registration Statement, the
Securities will constitute valid and legally binding obligations of the Company,
subject to bankruptcy, insolvency, fraudulent transfer, reorganization,
moratorium and similar laws of general applicability relating to or affecting
creditors' rights and to general equity principles.

     The foregoing opinion is limited to the Federal laws of the United States,
the laws of the State of New York and the General Corporation Law of the State
of Delaware, and we are expressing no opinion as to the effect of the laws of
any other jurisdiction.

     We have relied as to certain factual matters on information obtained from
public officials, officers of the Company and other sources believed by us to be
responsible,



American International Group, Inc.,                                          -3-


and we have assumed that the Indenture has been duly authorized, executed and
delivered by the Trustee, that the Securities will conform to the specimens
thereof examined by us and that the signatures on all documents examined by us
are genuine, assumptions which we have not independently verified.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us under the heading "Validity of
the Notes" in the Prospectus. In giving such consent, we do not thereby admit
that we are in the category of persons whose consent is required under Section 7
of the Act.

                                        Very truly yours,



                                        SULLIVAN & CROMWELL LLP