<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-10-23</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000769520</issuerCik>
        <issuerName>MIDDLEBY CORP</issuerName>
        <issuerTradingSymbol>midd</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001242670</rptOwnerCik>
            <rptOwnerName>WHITMAN WILLIAM F III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>8050 S.E. LITTLE HARBOUR DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>H7</rptOwnerStreet2>
            <rptOwnerCity>HOBE SOUND</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33455</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>1</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Chairman of the Board</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-10-23</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>100000</value>
<footnoteId id="F1"></footnoteId>
</transactionShares>
<transactionPricePerShare><value>7.094</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>2003571</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-10-24</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>20000</value>
<footnoteId id="F2"></footnoteId>
</transactionShares>
<transactionPricePerShare><value>5.90</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>2023571</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeTransaction><securityTitle><value>Common Stock</value>
</securityTitle>
<transactionDate><value>2003-10-23</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>F</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>44797</value>
<footnoteId id="F3"></footnoteId>
</transactionShares>
<transactionPricePerShare><value>18.47</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>1978774</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</nonDerivativeTransaction>
</nonDerivativeTable>
<derivativeTable><derivativeTransaction><securityTitle><value>Stock Option</value>
</securityTitle>
<conversionOrExercisePrice><value>7.094</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-10-23</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>100000</value>
<footnoteId id="F1"></footnoteId>
</transactionShares>
<transactionPricePerShare><footnoteId id="F1"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2003-06-23</value>
</exerciseDate>
<expirationDate><value>2008-02-19</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>100000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>150000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
<derivativeTransaction><securityTitle><value>Stock Option</value>
</securityTitle>
<conversionOrExercisePrice><value>5.90</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-10-23</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>20000</value>
<footnoteId id="F2"></footnoteId>
</transactionShares>
<transactionPricePerShare><footnoteId id="F2"></footnoteId>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2003-02-26</value>
</exerciseDate>
<expirationDate><value>2012-02-26</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>20000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>130000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
<derivativeTransaction><securityTitle><value>Stock Option</value>
</securityTitle>
<conversionOrExercisePrice><value>18.47</value>
</conversionOrExercisePrice>
<transactionDate><value>2003-10-23</value>
</transactionDate>
<transactionCoding><transactionFormType>4</transactionFormType>
<transactionCode>A</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionAmounts><transactionShares><value>45000</value>
<footnoteId id="F4"></footnoteId>
</transactionShares>
<transactionPricePerShare><value>18.47</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode><value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate><value>2003-10-23</value>
</exerciseDate>
<expirationDate><value>2013-10-23</value>
</expirationDate>
<underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares><value>45000</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts><sharesOwnedFollowingTransaction><value>175000</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature><directOrIndirectOwnership><value>D</value>
</directOrIndirectOwnership>
</ownershipNature>
</derivativeTransaction>
</derivativeTable>
<footnotes><footnote id="F1">This exercise is related to an option grant dated February 19, 1998 for 100,000 shares at a exercise price of $7.094. The option is fully exercised.</footnote>
<footnote id="F2">This exercise is related to an option grant dated February 26, 2002 for 20,000 shares at a exercise price of $5.90. The option grant is 20% exercised.</footnote>
<footnote id="F3">Represents the redemption of 44,797 shares to the Company as payment for the two option exercise transactions of 100,000 and 20,000 shares respectively</footnote>
<footnote id="F4">Represents an option grant for 45,000 shares under the Company's 1998 Stock Incentive Plan, as amended,at a exercise price of $18.47 which vest immediately and expire in 10 years.</footnote>
</footnotes>
<ownerSignature><signatureName>William F. Whitman, Jr.</signatureName>
<signatureDate>2003-10-27</signatureDate>
</ownerSignature>
</ownershipDocument>

