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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 QfgEMq1LL3AI2OHCsssCGXw7D6NOmwEYwc1uJSYB/nnDKVJEE67AF6Yko5lfNKyz
 7bGGqHVP2ZKGxlb45xSmRg==

<SEC-DOCUMENT>0001179110-05-013880.txt : 20050706
<SEC-HEADER>0001179110-05-013880.hdr.sgml : 20050706
<ACCEPTANCE-DATETIME>20050706175328
ACCESSION NUMBER:		0001179110-05-013880
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050701
FILED AS OF DATE:		20050706
DATE AS OF CHANGE:		20050706

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ACUSPHERE INC
		CENTRAL INDEX KEY:			0001115143
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				043208947
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		500 ARSENAL ST
		CITY:			WATERTOWN
		STATE:			MA
		ZIP:			02472
		BUSINESS PHONE:		6175778800

	MAIL ADDRESS:	
		STREET 1:		500 ARSENAL ST
		CITY:			WATERTOWN
		STATE:			MA
		ZIP:			02472

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Fenwick Sandra L
		CENTRAL INDEX KEY:			0001302954

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-50405
		FILM NUMBER:		05941818

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		617-686-8800

	MAIL ADDRESS:	
		STREET 1:		C/O ACUSPHERE, INC.
		STREET 2:		500 ARSENAL STREET
		CITY:			WATERTOWN
		STATE:			MA
		ZIP:			02472
</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>2005-07-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001115143</issuerCik>
        <issuerName>ACUSPHERE INC</issuerName>
        <issuerTradingSymbol>ACUS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001302954</rptOwnerCik>
            <rptOwnerName>Fenwick Sandra L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACUSPHERE, INC., 500 ARSENAL STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WATERTOWN</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02472</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2005-07-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1136</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.95</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1136</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">In connection with the Company's compensation program for non-employee directors, Ms. Fenwick elected to receive the second quarterly installment of her annual retainer for board and committee membership ($5,625.00) in the form of stock.  This second installment was payable on July 1, 2005, and was based on the closing price of the Company's Common Stock on the Nasdaq National Market on July 1, 2005 ($4.95).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: /s/ John F. Thero,  Attorney-in-Fact for Sandra L. Fenwick</signatureName>
        <signatureDate>2005-07-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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