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    <schemaVersion>X0306</schemaVersion>

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    <periodOfReport>2013-04-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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    <form4TransactionsReported>0</form4TransactionsReported>

    <issuer>
        <issuerCik>0000006207</issuerCik>
        <issuerName>AMREP CORP.</issuerName>
        <issuerTradingSymbol>AXR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000918213</rptOwnerCik>
            <rptOwnerName>KARABOTS NICK G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P O BOX 736</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FORT WASHINGTON</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19034</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
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            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Common Stock</value>
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            <transactionDate>
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            </transactionDate>
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                </transactionShares>
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                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                </transactionShares>
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                <directOrIndirectOwnership>
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                    <value>See Footnote</value>
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        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
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                <transactionFormType></transactionFormType>
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        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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            <transactionDate>
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            </transactionDate>
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                    <value>D</value>
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                    <value>372000</value>
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                    <value>See Footnote</value>
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                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
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        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-04-08</value>
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                <value></value>
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                <transactionShares>
                    <value>170000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
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                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                    <value>202000</value>
                </sharesOwnedFollowingTransaction>
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                    <value>D</value>
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                <value>Common Stock</value>
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                <transactionFormType></transactionFormType>
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                    <value>1391180</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
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                <transactionFormType></transactionFormType>
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                    <value>410000</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
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                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This transaction represents a charitable donation.</footnote>
        <footnote id="F2">The shares are owned by Glendi Publications, Inc., of which Mr. Karabots may be deemed to be a controlling person.</footnote>
        <footnote id="F3">The shares are owned by Kappa Media group, Inc., of which Mr. Karabots may be deemed to be a controlling person.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Nicholas G. Karabots</signatureName>
        <signatureDate>2013-06-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
