-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 SuSHz3UzYYrKM9feIdueDwnRNNvWEe6r3qaoYg75CXUbzbeUDzPJ/2tQ6n1mWIAH
 lYguHPzosRsO4Dw19pqU7Q==

<SEC-DOCUMENT>0001162675-08-000039.txt : 20080527
<SEC-HEADER>0001162675-08-000039.hdr.sgml : 20080526
<ACCEPTANCE-DATETIME>20080527184028
ACCESSION NUMBER:		0001162675-08-000039
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080523
FILED AS OF DATE:		20080527
DATE AS OF CHANGE:		20080527

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ASPECT MEDICAL SYSTEMS INC
		CENTRAL INDEX KEY:			0000886235
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		IRS NUMBER:				954154357
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		141 NEEDHAM STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02464-1505
		BUSINESS PHONE:		(617) 559-7857

	MAIL ADDRESS:	
		STREET 1:		141 NEWTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02464-1505

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COGHILL CAPITAL MANAGEMENT LLC
		CENTRAL INDEX KEY:			0001162675
		STATE OF INCORPORATION:			IL
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24663
		FILM NUMBER:		08861908

	BUSINESS ADDRESS:	
		STREET 1:		1 N WACKER DR
		STREET 2:		STE 4350
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3123242000

	MAIL ADDRESS:	
		STREET 1:		1 N WACKER DR
		STREET 2:		STE 4350
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CCM MASTER QUALIFIED FUND LTD
		CENTRAL INDEX KEY:			0001235152
		STATE OF INCORPORATION:			E9

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24663
		FILM NUMBER:		08861909

	BUSINESS ADDRESS:	
		STREET 1:		ONE N WACKER DR
		STREET 2:		STE 4350
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3123242031

	MAIL ADDRESS:	
		STREET 1:		C/O MORGAN STANLEY FUND SERVICES (CAYMAN
		STREET 2:		LTD CENTURY YARD CRICKET SQ HUTCHINGS DR
		CITY:			PO BOX 2681 GEORGE TOWN
		STATE:			E9
		ZIP:			00000

	FORMER NAME:	
		FORMER CONFORMED NAME:	CCM MASTER FUND LTD
		DATE OF NAME CHANGE:	20030522

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COGHILL CLINT D
		CENTRAL INDEX KEY:			0001235155

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24663
		FILM NUMBER:		08861910

	BUSINESS ADDRESS:	
		STREET 1:		ONE N WACKER DR
		STREET 2:		STE 4725
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3123341104
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-23</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000886235</issuerCik>
        <issuerName>ASPECT MEDICAL SYSTEMS INC</issuerName>
        <issuerTradingSymbol>ASPM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235152</rptOwnerCik>
            <rptOwnerName>CCM MASTER QUALIFIED FUND LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MORGAN STANLEY FUND SERVICES (CAYMAN</rptOwnerStreet1>
            <rptOwnerStreet2>LTD CENTURY YARD CRICKET SQ HUTCHINGS DR</rptOwnerStreet2>
            <rptOwnerCity>PO BOX 2681 GEORGE TOWN</rptOwnerCity>
            <rptOwnerState>E9</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>CAYMAN ISLANDS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001162675</rptOwnerCik>
            <rptOwnerName>COGHILL CAPITAL MANAGEMENT LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1 N WACKER DR</rptOwnerStreet1>
            <rptOwnerStreet2>STE 4350</rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235155</rptOwnerCik>
            <rptOwnerName>COGHILL CLINT D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1></rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity></rptOwnerCity>
            <rptOwnerState></rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Convertible Debt</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.07</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-05-23</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>54</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2014-03-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-06-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>ASPM Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>57682</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>550198</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Convertible Debt</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>19.07</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2014-03-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-06-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>ASPM Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>57682</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>550198</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Indirectly by Coghill Capital Management, LLC and Clint D. Coghill</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">These securities may be deemed to be beneficially owned by Coghill Capital Management, L.L.C.  (&quot;CCM&quot;), the investment manager of CCM Master Qualified Fund, Ltd. (the &quot;Master Fund&quot;).  These securities may also be deemed to be beneficially owned by Clint Coghill, the President and majority owner of CCM.  Each of CCM and Mr. Coghill disclaims beneficial ownership of the reported securities except to the extent of its pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>CCM Master Qualified Fund, Ltd</signatureName>
        <signatureDate>2008-05-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Coghill Capital Management, LLC</signatureName>
        <signatureDate>2008-05-27</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Clint D Coghill</signatureName>
        <signatureDate>2008-05-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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