<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2007-09-05</periodOfReport>

    <dateOfOriginalSubmission>2007-09-07</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000005272</issuerCik>
        <issuerName>AMERICAN INTERNATIONAL GROUP INC</issuerName>
        <issuerTradingSymbol>AIG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001236615</rptOwnerCik>
            <rptOwnerName>STARR INTERNATIONAL CO INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>101 BAARERSTRASSE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CH 6300 ZUG</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>41</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>240076070</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <remarks>The Form 4 filed by Starr International Company, Inc. on September 7, 2007 inadvertently reflected information that should have been reported by C.V. Starr &amp;  Co., Inc. Trust in connection with its sale of common stock of American International Group, Inc. on September 5, 2007. For the avoidance of doubt, no shares of common stock of American International Group, Inc. were sold by Starr International Company, Inc. on September 5, 2007.

Starr International Company, Inc. may be deemed to beneficially own more than 10% of the common stock of American International Group, Inc. under Rule 16a-1(a)(1) under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;), as a result of it being deemed a member of a group under Section 13(d)(3) of the Exchange Act.</remarks>

    <ownerSignature>
        <signatureName>/s/ Stuart Osborne,                        Vice President, on behalf of Starr International Company, Inc.</signatureName>
        <signatureDate>2007-09-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
