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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-02-14</periodOfReport>

    <issuer>
        <issuerCik>0001077800</issuerCik>
        <issuerName>TECHNEST HOLDINGS INC</issuerName>
        <issuerTradingSymbol>THNS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001102833</rptOwnerCik>
            <rptOwnerName>MARKLAND TECHNOLOGIES INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>90 GROVE STREET, SUITE 205</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>RIDGEFIELD,</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06877</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-02-14</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2005-02-14</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>412650577</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>7000000.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>412650577</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Securities acquired pursuant to a Securities Purchase Agreement between Markland Technologies, Inc. and Technest Holdings, Inc. dated February 14, 2005.</footnote>
        <footnote id="F2">The Securities Purchase Agreement between Markland Technologies, Inc. and Technest Holdings, Inc. dated February 14, 2005, and attached to our Current Report on Form 8-K filed on February 15, 2005, provides us a right of first refusal should their ownership in Technest Holdings, Inc. fall below certain levels. Therefore, Markland Technologies, Inc. may have a contractual right to acquire additional shares of in the future.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Robert Tarini, CEO &amp; Chairman of the Board of Directors</signatureName>
        <signatureDate>2005-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
