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

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-05-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000109156</issuerCik>
        <issuerName>ZALE CORP</issuerName>
        <issuerTradingSymbol>ZLC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001376259</rptOwnerCik>
            <rptOwnerName>Breeden Capital Management LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001368419</rptOwnerCik>
            <rptOwnerName>Breeden Partners L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001370407</rptOwnerCik>
            <rptOwnerName>BREEDEN PARTNERS (CALIFORNIA) L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001433080</rptOwnerCik>
            <rptOwnerName>BREEDEN PARTNERS (CALIFORNIA) II LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001448125</rptOwnerCik>
            <rptOwnerName>BREEDEN PARTNERS (NEW YORK) I L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001423997</rptOwnerCik>
            <rptOwnerName>Breeden Capital Partners LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001300622</rptOwnerCik>
            <rptOwnerName>Breeden Richard C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BREEDEN CAPITAL MANAGEMENT LLC</rptOwnerStreet1>
            <rptOwnerStreet2>100 NORTHFIELD STREET</rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</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>2012-05-15</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>256343</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.27</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5679071</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares of Common Stock beneficially owned by the Reporting Owners directly following the sale by Breeden Partners (New York) I L.P. of all of its 256,343 shares are as follows: 33,686 shares by Breeden Partners L.P., 4,882,668 shares by Breeden Partners (California) L.P., 743,657 shares by Breeden Partners (California) II L.P, 10,942 shares by Richard C. Breeden  and 19,060 shares by Breeden Capital Partners LLC (reflecting a distribution of 19,060 shares from Breeden Partners Holdco Ltd.).</footnote>
        <footnote id="F2">The shares of Common Stock beneficially owned by the Reporting Owners indirectly following sale by Breeden Partners (New York) I L.P. of all of its 256,343 shares are as follows: 5,660,011 shares by Breeden Capital Partners LLC, 5,679,071 shares by Richard C. Breeden (after indirectly selling 256,343 shares in the reported transactions) and 5,679,071 shares by Breeden Capital Management LLC (after indirectly selling 256,343 shares in the reported transaction); however, each such Reporting Owner disclaims beneficial ownership of such shares except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F3">Richard C. Breeden  is the managing member of Breeden Capital Partners, LLC, managing member and Chairman and Chief Executive of Breeden Capital Management LLC and the Key Principal of Breeden Partners (Cayman) Ltd., and, as such, may be deemed to be the indirect beneficial owner of the shares of Common Stock owned by Breeden Partners L.P., Breeden Partners (California) L.P., Breeden Partners (California) II L.P., and Breeden Partners (New York) I L.P., however, he disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F4">Breeden Capital Management LLC is principally involved in the business of providing investment advisory and investment management services to Breeden Partners L.P., Breeden Partners (California) L.P., Breeden Partners(California) II L.P., and Breeden Partners (New York) I L.P., (together, the &quot;Fund&quot;) and, among other things, exercises all voting and other powers and privileges attributable to any securities held for the account of the Fund and, as such, may be deemed to be the indirect beneficial owner of the shares of Common Stock owned by the Fund; however, it disclaims beneficial ownership of such shares except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F5">Breeden Capital Partners LLC is the general partner of Breeden Partners L.P., Breeden Partners (California) L.P., Breeden Partners (California) II L.P. and Breeden Partners (New York) I L.P., and, as such, may be deemed to beneficially own the shares of common stock owned by Breeden Partners L.P., Breeden Partners (California) L.P., Breeden Partners (California) II L.P. and Breeden Partners (New York) I L.P.; however it disclaims beneficial ownership of such shares except to the extent of its pecuniary interest therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Richard C. Breeden - See signatures included in Exhibit 99.1</signatureName>
        <signatureDate>2012-05-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
