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

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-01-20</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000771252</issuerCik>
        <issuerName>DIGITAL ANGEL CORP</issuerName>
        <issuerTradingSymbol>DOC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252182</rptOwnerCik>
            <rptOwnerName>NIEUWSMA KEVIN L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>490 VILLAUME AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUTH ST. PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55075</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Corporate Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option-Right to Buy</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.39</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-06-26</value>
            </exerciseDate>
            <expirationDate>
                <value>2012-06-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Shares of Common Stock, $0.005 par value per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option-Right to Buy</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.89</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-12-30</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-12-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Shares of Common Stock, $0.005 par value per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>200000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Option was granted by the Board of Directors on June 27, 2002 pursuant to the Digital Angel Corporation Transition Stock Option Plan.  The Option vests as to 33 1/3% of the option shares on each June 26, 2003, June 26, 2004 and June 26, 2005.</footnote>
        <footnote id="F2">The Option was granted by the Board of Directors on December 31, 2003 pursuant to the Digital Angel Corporation Transition Stock Option Plan.  The Option becomes exercisable on December 30, 2004.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Kevin L. Nieuwsma</signatureName>
        <signatureDate>2004-01-29</signatureDate>
    </ownerSignature>
</ownershipDocument>

