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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-11-13</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419222</rptOwnerCik>
            <rptOwnerName>Paz Ramon</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O HEARTWARE, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3351 EXECUTIVE WAY</rptOwnerStreet2>
            <rptOwnerCity>MIRAMAR</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Quality Assur.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Option to Purchase</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.67</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-11-13</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>400000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.67</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-11-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>400000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>400000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The exercise price of US$0.67 has been converted from AU$0.75 at the spot rate on the date of grant.</footnote>
        <footnote id="F2">The option vests based on performance criteria as follows:

25% upon the last to occur of the first anniversary of the grant date, the Company receiving CE mark, the Company filing its application for TGA approval or the commencement of the Company's Bridge-to-Transplant trial in the United States.

25% upon the last to occur of the second anniversary of the grant date or the completion of enrolment under the Company's Bridge-to-Transplant trial in the United States.

25% upon the last to occur of the third anniversary of the grant date, the Company filing an application for Pre-Market Approval with the United States Food and Drug Administration as a Bridge-to-Transplant therapy and the completion of enrolment under the Company's Destination Therapy clinical trial in the United States.

25% on the last to occur of the fourth anniversary of the grant date or the Company completing a human feasibility study for its next generation device, the MVAD.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ David McIntyre as Attorney-in-Fact</signatureName>
        <signatureDate>2007-11-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
