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

    <schemaVersion>X0202</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2004-04-30</periodOfReport>

    <dateOfOriginalSubmission>2004-05-10</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001031283</issuerCik>
        <issuerName>ENTRUST INC</issuerName>
        <issuerTradingSymbol>ENTU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001289779</rptOwnerCik>
            <rptOwnerName>Carey David T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>16633 DALLAS PARKWAY, SUITE 800</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ADDISON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75001</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and COO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.5</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>250000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Options</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>4.5</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-04-30</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">25% (62,500) of the original number of shares will vest immediately upon the Grant date; 1/24th of the remaining number of shares on that day of the month for each of the next 24 months thereafter</footnote>
        <footnote id="F2">2 year cliff vesting - 50% of the total number of shares granted will become exercisiable (vest) on the 2nd anniversary of the grant date.  The other 50% of shares will vest on the 4th anniversary of the grant date, OR accelerated vesting on the first day on which the closing price of the Company's Common Stock on the Nasdaq National Market (&quot;Nasdaq&quot;), as reported by Nasdaq, shall have been at least $15.00 per share for at least 50 out of 60 consecutive trading days, including the day of vesting pursuant to this clause, provided that the Executive remains employed with the Company as of such date. (which ever happens first)</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Sherry Crawford by power of attorney on behalf of David T Carey</signatureName>
        <signatureDate>2004-05-10</signatureDate>
    </ownerSignature>
</ownershipDocument>

