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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-07-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001389072</issuerCik>
        <issuerName>HeartWare LTD</issuerName>
        <issuerTradingSymbol>ASX:HTW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001404735</rptOwnerCik>
            <rptOwnerName>Wade Denis Newell</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HEARTWARE LIMITED, LEVEL 57</rptOwnerStreet1>
            <rptOwnerStreet2>MLC CENTRE, 19-29 MARTIN PLACE</rptOwnerStreet2>
            <rptOwnerCity>SYDNEY, NSW</rptOwnerCity>
            <rptOwnerState>C3</rptOwnerState>
            <rptOwnerZipCode>2000</rptOwnerZipCode>
            <rptOwnerStateDescription>AUSTRALIA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Ordinary shares</value>
            </securityTitle>
            <transactionDate>
                <value>2007-07-24</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.53</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1008333</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>see footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The purchase price of US$0.53 has been converted from AU$0.60 at the spot rate on the date of transaction.</footnote>
        <footnote id="F2">Nickeli Holdings Pty. Limited as Trustee of the Wade Superannuation Fund.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ David McIntyre as Attorney-in-Fact</signatureName>
        <signatureDate>2007-07-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
