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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-03-16</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001361113</issuerCik>
        <issuerName>VARONIS SYSTEMS INC</issuerName>
        <issuerTradingSymbol>VRNS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000821977</rptOwnerCik>
            <rptOwnerName>EVERGREEN IV L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EVERGREEN VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>25 HABARZEL ST.</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>69710</rptOwnerZipCode>
            <rptOwnerStateDescription>ISRAEL</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001601323</rptOwnerCik>
            <rptOwnerName>Evergreen IV GP, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EVERGREEN VENTURE PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>25 HABARZEL STREET</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>69710</rptOwnerZipCode>
            <rptOwnerStateDescription>ISRAEL</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001601327</rptOwnerCik>
            <rptOwnerName>Evergreen E.P.F IV Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EVERGREEN VENTURES PARTNERS</rptOwnerStreet1>
            <rptOwnerStreet2>25 HABARZEL STREET</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>69710</rptOwnerZipCode>
            <rptOwnerStateDescription>ISRAEL</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>2016-03-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2178</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.36</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3447407</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares directly held by Evergreen IV, L.P., the general partner of which is Evergreen IV GP, L.P., and the general partner of which is Evergreen Management Ltd.</footnote>
        <footnote id="F2">Evergreen IV GP, L.P. and Evergreen Management Ltd. are additional reporting persons and each has the same address as the reporting person listed above.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Evergreen IV, L.P. By: Evergreen IV GP, L.P., its sole General Partner, By: Evergreen Management Ltd, its sole General Partner /s/ Amichal Hammer, authorized signatories</signatureName>
        <signatureDate>2016-03-18</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Evergreen IV GP, L.P. By: Evergreen Management Ltd, its sole General Partner, /s/ Motti Hoss /s/ Amichai Hammer, authorized signatories</signatureName>
        <signatureDate>2016-03-18</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Evergreen Management, Ltd. /s/ Motti Hoss /s/ Amichai Hammer, authorized signatories</signatureName>
        <signatureDate>2016-03-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
