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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-08-29</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227161</rptOwnerCik>
            <rptOwnerName>KIRWAN WILLIAM E</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>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12544</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-08-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>30</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>24.5025</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5942</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">EACH SHARE OF PHANTOM STOCK IS PAYABLE IN 1 SHARE OF COMMON STOCK OF THE ISSUER.</footnote>
        <footnote id="F2">REFLECTS SHARES ACQUIRED PURSUANT TO THE DIVIDEND REINVESTMENT PROVISIONS OF THE ISSUER'S DEFERRED COMPENSATION PLAN.</footnote>
        <footnote id="F3">REFLECTS PHANTOM STOCK ACQUIRED THROUGH PARTICIPATION IN ISSUER'S DEFERRED COMPENSATION PLAN.  PHANTOM STOCK IS PAYABLE IN COMMON STOCK NOT EARLIER THAN SIX MONTHS AFTER TERMINATION OF REPORTING PERSON'S SERVICE AS A DIRECTOR OF THE ISSUER.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>DANA KLEIN, ATTORNEY-IN-FACT</signatureName>
        <signatureDate>2008-09-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0303
4
2008-08-29
0000105668
WENDYS INTERNATIONAL INC
WEN
0001227161
KIRWAN WILLIAM E
WENDY'S INTERNATIONAL, INC.
P. O. BOX 256
DUBLIN
OH
43017-0256
1
0
0
0
Common Stock
12544
D
Phantom Stock
0
2008-08-29
4
A
0
30
24.5025
A
Common Stock
30
5942
D
EACH SHARE OF PHANTOM STOCK IS PAYABLE IN 1 SHARE OF COMMON STOCK OF THE ISSUER.
REFLECTS SHARES ACQUIRED PURSUANT TO THE DIVIDEND REINVESTMENT PROVISIONS OF THE ISSUER'S DEFERRED COMPENSATION PLAN.
REFLECTS PHANTOM STOCK ACQUIRED THROUGH PARTICIPATION IN ISSUER'S DEFERRED COMPENSATION PLAN.  PHANTOM STOCK IS PAYABLE IN COMMON STOCK NOT EARLIER THAN SIX MONTHS AFTER TERMINATION OF REPORTING PERSON'S SERVICE AS A DIRECTOR OF THE ISSUER.
DANA KLEIN, ATTORNEY-IN-FACT
2008-09-03