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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-09-29</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000105668</issuerCik>
        <issuerName>WENDYS INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>WEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001189430</rptOwnerCik>
            <rptOwnerName>LEVIN JERRY W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>WENDY'S INTERNATIONAL, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>P. O. BOX 256</rptOwnerStreet2>
            <rptOwnerCity>DUBLIN</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>43017-0256</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-09-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7148</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>OPTION (RIGHT  TO PURCHASE)</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>28.705</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-09-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>6244</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-09-29</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-04-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6244</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>OPTION (RIGHT  TO PURCHASE)</value>
                <footnoteId id="F3"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>37.63</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-09-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4310</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-05-01</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4310</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F3">DISPOSITION WAS PURSUANT TO THE CONSUMMATION OF THE AGREEMENT AND PLAN OF MERGER, DATED AS OF APRIL 23, 2008, AMONG TRIARC COMPANIES, INC., GREEN MERGER SUB, INC. AND WENDY'S INTERNATIONAL, INC. (THE &quot;MERGER AGREEMENT&quot;).  UNDER THE MERGER AGREEMENT EACH OPTION TO PURCHASE A WENDY'S COMMON SHARE BECAME FULLY VESTED AND WAS CONVERTED TO AN OPTION TO PURCHASE 4.25 COMMON SHARES OF THE COMBINED COMPANY, WENDY'S/ARBY'S GROUP, INC., AS OF THE EFFECTIVE TIME OF THE MERGER, SEPTEMBER 29, 2008.  THE OPTION EXERCISE PRICE FOR EACH OPTION TO PURCHASE A WENDY'S COMMON SHARE WAS DIVIDED BY 4.25.  THE CLOSING PRICE OF WENDY'S COMMON SHARES WAS $19.21 PER SHARE ON THAT DATE.</footnote>
        <footnote id="F1">SHARES SHOWN ON TABLE 1 INCLUDE SHARES ACQUIRED PURSUANT TO THE DIVIDEND EQUIVALENT RIGHT PROVISIONS OF RESTRICTED STOCK UNIT AWARDS MADE UNDER THE ISSUER'S 2003 STOCK INCENTIVE PLAN.</footnote>
        <footnote id="F2">DISPOSITION WAS PURSUANT TO THE CONSUMMATION OF THE AGREEMENT AND PLAN OF MERGER, DATED AS OF APRIL 23, 2008, AMONG TRIARC COMPANIES, INC., GREEN MERGER SUB, INC. AND WENDY'S INTERNATIONAL, INC. (THE &quot;MERGER AGREEMENT&quot;).  UNDER THE MERGER AGREEMENT EACH WENDY'S COMMON SHARE BECAME FULLY VESTED AND WAS CONVERTED TO 4.25 COMMON SHARES OF THE COMBINED COMPANY, WENDY'S/ARBY'S GROUP, INC., AS OF THE EFFECTIVE TIME OF THE MERGER, SEPTEMBER 29, 2008.  THE CLOSING PRICE OF WENDY'S COMMON SHARES WAS $19.21 PER SHARE ON THAT DATE.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>DANA KLEIN, ATTORNEY-IN-FACT</signatureName>
        <signatureDate>2008-10-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
