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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2010-06-16</periodOfReport>

    <dateOfOriginalSubmission>2010-06-18</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0001014739</issuerCik>
        <issuerName>BioScrip, Inc.</issuerName>
        <issuerTradingSymbol>BIOS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001257435</rptOwnerCik>
            <rptOwnerName>WOODWARD GORDON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>111 RADIO CIRCLE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MOUNT KISCO</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10549</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOther>1</isOther>
            <otherText>(see remarks below)</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $.0001 Par Value</value>
            </securityTitle>
            <transactionDate>
                <value>2010-06-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the terms of an Assignment and Transfer Agreement entered into on July 7, 2010, Mr. Woodward transferred his pecuniary interest in these shares to Kohlberg &amp; Co., LLC, but has retained all voting and dispositive power with respect to such shares. Mr. Woodward disclaims beneficial ownership of such shares except to the extent of his pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>Mr. Woodward was initially appointed to the board of directors of the Issuer on March 25, 2010 as the designee of Kohlberg Investors V, L.P. Kohlberg Management V, L.L.C is the general partner of Kohlberg Investors V, L.P. Mr. Woodward is a member and Vice President of Kohlberg Management V, L.L.C and a member of its Operating Committee.</remarks>

    <ownerSignature>
        <signatureName>/s/ Gordon H. Woodward</signatureName>
        <signatureDate>2010-07-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
