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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-09-30</periodOfReport>

    <dateOfOriginalSubmission>2015-11-03</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001476170</issuerCik>
        <issuerName>Unilife Corp</issuerName>
        <issuerTradingSymbol>UNIS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001483243</rptOwnerCik>
            <rptOwnerName>Shortall Alan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O 250 CROSS FARM LANE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>YORK</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>17406</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10709043</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>55074</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On November 3, 2015, the reporting person mistakenly filed a Form 4 reporting both a disposition of 2,951,668 shares of common stock on September 30, 2015 and an acquisition of 2,951,668 shares of common stock on October 26, 2015.  This report amends the filing originally made on November 3, 2015 to delete in their entirety both of such transactions.  On September 30, 2015, an event of default occurred with respect to certain loans made by an unaffiliated third party to Alan Shortall, under which an aggregate of 2,951,668 shares of common stock were pledged as collateral by Mr. Shortall.  The lender took no action to terminate the agreement or seize or acquire the share collateral upon such event of default, and the parties instead entered into an amendment to the original loan agreement pursuant to which Mr. Shortall pledged additional collateral to the lender and the default was cured.  The loan continued in effect until a subsequent default occurred on December 9, 2015, which was</footnote>
        <footnote id="F2">(Continued from footnote 1) reported on a Form 4 on such date.  As of October 26, 2015, the reporting person owned 10,709,043 shares of common stock.</footnote>
        <footnote id="F3">Owned by spouse of Mr. Shortall</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Alan Shortall</signatureName>
        <signatureDate>2016-02-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
