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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-06-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000921738</issuerCik>
        <issuerName>PENN NATIONAL GAMING INC</issuerName>
        <issuerTradingSymbol>PENN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001217821</rptOwnerCik>
            <rptOwnerName>CRAMER HAROLD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>825 BERKSHIRE BLVD SUITE 200</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WYOMISSING</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19610</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-06-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9521104</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by Trust</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares are owned by The Carlino Family Trust, a greater than ten percent owner of the issuer and indirectly owned by Harold Cramer, Peter D. Carlino, Richard J. Carlino, David E. Carlino and Peter M. Carlino, the trustees of the Carlino Family Trust. The Carlino Family Trust distributed 12,500 shares to a beneficiary of the trust. Harold Cramer is a trustee of The Carlino Family Trust, and has been given, by letter agreement, certain rights with respect to voting and/or dispositions from the trust, and a director of the issuer and is reporting this transaction on behalf of The Carlino Family Trust.</footnote>
        <footnote id="F2">The reporting person is also the indirect beneficial owner of 502,212 shares owned by a  residuary trust for the benefit of Peter D. Carlino and Peter D. Carlino's grandchildren as to which he is a trustee. Mr. Cramer disclaims beneficial ownership of the shares owned by The Carlino Family Trust and the residuary trust, and this report should not be deemed an admission that Harold Cramer is the beneficial owner of such securities for the purpose of section 16 or any other purpose. In addition, Mr. Cramer directly owns 60,000 shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Robert S. Ippolito as attorney-in-fact for Harold Cramer</signatureName>
        <signatureDate>2008-06-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
