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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2018-05-08</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001629261</issuerCik>
        <issuerName>Long Blockchain Corp.</issuerName>
        <issuerTradingSymbol>LBCC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001751099</rptOwnerCik>
            <rptOwnerName>Court Cavendish Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>THE CARE HOUSE, RANDALLS WAY</rptOwnerStreet1>
            <rptOwnerStreet2>LEATHERHEAD</rptOwnerStreet2>
            <rptOwnerCity>SURREY</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>KT22 7TW</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001751732</rptOwnerCik>
            <rptOwnerName>Patel Chai</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O COURT CAVENDISH LTD., THE CARE HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>RANDALLS WAY, LEATHERHEAD</rptOwnerStreet2>
            <rptOwnerCity>SURREY</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>KT22 7TW</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>512733</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>3.00</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-12-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2020-12-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>100000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>.50</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2018-05-08</value>
            </exerciseDate>
            <expirationDate>
                <value>2022-05-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1200000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Convertible Note</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>.40</value>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2017-12-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2018-12-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>7803312</value>
                    <footnoteId id="F3"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The reported securities are owned directly by Court Cavendish Ltd. and indirectly by Dr. Chai Patel, as officer, director, and majority shareholder of Court Cavendish Ltd. Dr. Patel disclaims beneficial ownership of the securities except to the extent of his pecuniary interest therein.</footnote>
        <footnote id="F2">The Issuer and Court Cavendish Ltd. entered into a Loan and Option Agreement on 12/21/17, which was amended and restated on 5/4/18. To date, the Issuer has made drawdowns in the aggregate principal amount of $3,000,000, of which $750,000, plus accrued interest thereon, has been converted into shares of common stock. Interest on the outstanding principal amount accrues at the rate of 12.5% per annum and is payable quarterly in cash or common stock at $0.40 per share, at the Issuer's option. The principal and unpaid accrued interest is due and payable on 12/21/18 in cash or shares of common stock valued at $0.40 per share, at Court Cavendish Ltd.'s option. Court Cavendish Ltd. also has the option, exercisable at any time prior to maturity, to convert the outstanding principal and unpaid accrued interest into shares of common stock at a price per share such that the average conversion price of all shares issued to Court Cavendish Ltd. upon conversion is $0.40 per share.</footnote>
        <footnote id="F3">Assumes conversion of the aggregate principal amount of the note and all accrued interest on 12/21/18, less the previous conversion of $750,000 in principal plus accrued interest thereon into 250,233 shares of common stock at a price of $3.00 per share on 12/26/17.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Catherine Valenti, as director of Court Cavendish Ltd.</signatureName>
        <signatureDate>2018-08-30</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Dr. Chai Patel</signatureName>
        <signatureDate>2018-08-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
