-----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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 LACdJZikx+tapE416wbE7g==

<SEC-DOCUMENT>0001005477-09-002154.txt : 20090501
<SEC-HEADER>0001005477-09-002154.hdr.sgml : 20090501
<ACCEPTANCE-DATETIME>20090501170824
ACCESSION NUMBER:		0001005477-09-002154
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090430
FILED AS OF DATE:		20090501
DATE AS OF CHANGE:		20090501

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NIERENBERG INVESTMENT MANAGEMENT CO
		CENTRAL INDEX KEY:			0001282683

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790342

	MAIL ADDRESS:	
		STREET 1:		19605 NE 8TH ST
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			D3 FAMILY FUND LP
		CENTRAL INDEX KEY:			0001282685

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790340

	MAIL ADDRESS:	
		STREET 1:		19605 NE 8TH ST
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NIERENBERG DAVID
		CENTRAL INDEX KEY:			0001040899

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790338

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NATUS MEDICAL INC
		CENTRAL INDEX KEY:			0000878526
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		IRS NUMBER:				770154833
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1501 INDUSTRIAL ROAD
		CITY:			SAN CARLOS
		STATE:			CA
		ZIP:			94070
		BUSINESS PHONE:		6508020400

	MAIL ADDRESS:	
		STREET 1:		1501 INDUSTRIAL ROAD
		CITY:			SAN CARLOS
		STATE:			CA
		ZIP:			94070

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DIII OFFSHORE FUND LP
		CENTRAL INDEX KEY:			0001282684

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790341

	BUSINESS ADDRESS:	
		STREET 1:		19605 NE 8TH ST
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607
		BUSINESS PHONE:		360-604-8600

	MAIL ADDRESS:	
		STREET 1:		19605 NE 8TH ST
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607

	FORMER NAME:	
		FORMER CONFORMED NAME:	D3 OFFSHORE FUND LP
		DATE OF NAME CHANGE:	20040304

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			D3 Family Bulldog Fund LP
		CENTRAL INDEX KEY:			0001365745

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790339

	BUSINESS ADDRESS:	
		STREET 1:		19605 NE 8TH STREET
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607
		BUSINESS PHONE:		360-604-8600

	MAIL ADDRESS:	
		STREET 1:		19605 NE 8TH STREET
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Nierenberg Investment Management Offshore Inc
		CENTRAL INDEX KEY:			0001365764
		STATE OF INCORPORATION:			C5
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-33001
		FILM NUMBER:		09790343

	BUSINESS ADDRESS:	
		STREET 1:		MONTAGUE STERLING CENTRE
		STREET 2:		3RD FLOOR
		CITY:			NASSAU
		STATE:			C5
		ZIP:			00000
		BUSINESS PHONE:		360-604-8600

	MAIL ADDRESS:	
		STREET 1:		19605 NE 8TH STREET
		CITY:			CAMAS
		STATE:			WA
		ZIP:			98607
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar123.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-04-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000878526</issuerCik>
        <issuerName>NATUS MEDICAL INC</issuerName>
        <issuerTradingSymbol>BABY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001365764</rptOwnerCik>
            <rptOwnerName>Nierenberg Investment Management Offshore Inc</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001282683</rptOwnerCik>
            <rptOwnerName>NIERENBERG INVESTMENT MANAGEMENT CO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001282684</rptOwnerCik>
            <rptOwnerName>DIII OFFSHORE FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001282685</rptOwnerCik>
            <rptOwnerName>D3 FAMILY FUND LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001365745</rptOwnerCik>
            <rptOwnerName>D3 Family Bulldog Fund LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001040899</rptOwnerCik>
            <rptOwnerName>NIERENBERG DAVID</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>19605 NE 8TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMAS</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98607</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>134000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>550291</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By The D3 Family Fund, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>230000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2339995</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By The D3 Family Bulldog Fund, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-04-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>136000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>581827</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By The DIII Offshore Fund, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>129931</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By The D3 Family Canadian Fund, LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Each of the reporting persons disclaims beneficial ownership of these securities except to the extent of the reporting person's pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>David Nierenberg, President, Nierenberg Investment Management Company, Inc. (NIMCO)</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David Nierenberg, President, Nierenberg Investment Management Offshore, Inc. (NIMO)</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David Nierenberg, President, NIMO, General Partner of The DIII Offshore Fund, L.P.</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David Nierenberg, President, NIMCO, General Partner of The D3 Family Fund, L.P.</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David Nierenberg, President, NIMCO, General Partner of The D3 Family Bulldog Fund, L.P.</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>David Nierenberg</signatureName>
        <signatureDate>2009-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----