-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
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 4mOl50y/t0yQg9DMwgvmIw==

<SEC-DOCUMENT>0001179110-05-014400.txt : 20050718
<SEC-HEADER>0001179110-05-014400.hdr.sgml : 20050718
<ACCEPTANCE-DATETIME>20050718171656
ACCESSION NUMBER:		0001179110-05-014400
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050714
FILED AS OF DATE:		20050718
DATE AS OF CHANGE:		20050718

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NMT MEDICAL INC
		CENTRAL INDEX KEY:			0001017259
		STANDARD INDUSTRIAL CLASSIFICATION:	SURGICAL & MEDICAL INSTRUMENTS & APPARATUS [3841]
		IRS NUMBER:				954090463
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		27 WORMWOOD STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210
		BUSINESS PHONE:		6177370930

	MAIL ADDRESS:	
		STREET 1:		27 WORMWOOD STREET
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02210

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NITINOL MEDICAL TECHNOLOGIES INC
		DATE OF NAME CHANGE:	19960619

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			WHITNEY JH & CO
		CENTRAL INDEX KEY:			0000901399

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21001
		FILM NUMBER:		05960037

	BUSINESS ADDRESS:	
		STREET 1:		177 BROAD STREET
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06901
		BUSINESS PHONE:		2039731400
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-07-14</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001017259</issuerCik>
        <issuerName>NMT MEDICAL INC</issuerName>
        <issuerTradingSymbol>NMTI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000901399</rptOwnerCik>
            <rptOwnerName>WHITNEY JH &amp; CO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>177 BROAD STREET, 15TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>STAMFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>113793</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <transactionDate>
                <value>2005-07-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1829010</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.8620</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote 1.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <transactionDate>
                <value>2005-07-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>561207</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote 2.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Securities owned by Whitney Equity Partners, L.P. (&quot;Equity Partners&quot;).</footnote>
        <footnote id="F2">Securities owned by Whitney Subordinated Debt Fund, L.P. (&quot;Debt Fund&quot;).</footnote>
        <footnote id="F3">Securities distributed to partners of the Equity Partners on a pro-rata basis in accordance with the Partnership Agreement.</footnote>
        <footnote id="F4">Securities distributed to partners of Debt Fund on a pro-rata basis in accordance with the Partnership Agreement.</footnote>
    </footnotes>

    <remarks>The undersigned may be deemed to be a member of a Section 13(d) &quot;group&quot; with Equity Partners and Debt Fund.  The undersigned disclaims the existence of such a group and disclaims beneficial ownership of any shares owned by Equity Partners and Debt Fund.</remarks>

    <ownerSignature>
        <signatureName>J. H. WHITNEY &amp; CO., By:  Whitney General Partner, L.L.C., General Partner, By:  Daniel J. O'Brien, Managing Member</signatureName>
        <signatureDate>2005-07-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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