-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001179110-05-014445.txt : 20050719
<SEC-HEADER>0001179110-05-014445.hdr.sgml : 20050719
<ACCEPTANCE-DATETIME>20050719140013
ACCESSION NUMBER:		0001179110-05-014445
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050714
FILED AS OF DATE:		20050719
DATE AS OF CHANGE:		20050719

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:			FORDYCE JAMES H
		CENTRAL INDEX KEY:			0001239600

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21001
		FILM NUMBER:		05961286

	BUSINESS ADDRESS:	
		STREET 1:		WHITNEY & CO.
		STREET 2:		177 BROAD STREET
		CITY:			STAMFORD
		STATE:			CT
		ZIP:			06901
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

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

    <dateOfOriginalSubmission>2005-07-18</dateOfOriginalSubmission>

    <notSubjectToSection16>1</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001239600</rptOwnerCik>
            <rptOwnerName>FORDYCE JAMES H</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>
        <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>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 1.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>113793</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote 2.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Securities owned by Whitney Subordinated Debt Fund, L.P. (&quot;Debt Fund&quot;). The undersigned disclaims beneficial ownership of such shares except to the extent of his proportionate interest.</footnote>
        <footnote id="F2">Securities owned by J. H. Whitney &amp; Co. (&quot;JHW&amp;Co.&quot;).  The undersigned disclaims beneficial ownership of such shares except to the extent of his proportionate interest.</footnote>
        <footnote id="F3">Securities distributed to partners of Debt Fund on a pro-rata basis in accordance with the Partnership Agreement.</footnote>
    </footnotes>

    <remarks>Whitney Equity Partnes, L.P., Debt Fund and JHW&amp;Co. may be deemed members of a Section 13(d) &quot;group&quot;.  The undersigned disclaims the existence of such a group and disclaims beneficial ownership of the Common Stock owned by such partnerships, except as set forth in Footnotes 1 and 2.</remarks>

    <ownerSignature>
        <signatureName>James H. Fordyce, By:  Daniel J. O'Brien, Attorney-in-Fact</signatureName>
        <signatureDate>2005-07-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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