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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-21</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>24 RAOUL WALLENBERG ST.</rptOwnerStreet1>
            <rptOwnerStreet2>ZIV TOWERS, BUILDING B, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>6971920</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>24 RAOUL WALLENBERG ST.</rptOwnerStreet1>
            <rptOwnerStreet2>ZIV TOWERS, BUILDING B, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>6971920</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>24 RAOUL WALLENBERG ST.</rptOwnerStreet1>
            <rptOwnerStreet2>ZIV TOWERS, BUILDING B, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>TEL AVIV</rptOwnerCity>
            <rptOwnerState>L3</rptOwnerState>
            <rptOwnerZipCode>6971920</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>2017-03-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>577</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>29.11</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2817602</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <remarks>1.  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.

2.  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.</remarks>

    <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>2017-03-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Evergreen IV GP, L.P. By: Evergreen Management Ltd, its sole General Partner, /s/ Motti Hoss /s/ Amichal Hamer, authorized signatories</signatureName>
        <signatureDate>2017-03-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Evergreen Management Ltd. /s/ Motti Hoss /s/ Amichal Hamer, authorized signatories</signatureName>
        <signatureDate>2017-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
