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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,
 RbUA/+R0mz8hGgl2O6CWjWahzknO6CsawnpKSRKWMtgA08g5V9vBTtjnBPq0KtQd
 gnVrf7xUvZNIeyn+913ojA==

<SEC-DOCUMENT>0001181431-05-034345.txt : 20050613
<SEC-HEADER>0001181431-05-034345.hdr.sgml : 20050613
<ACCEPTANCE-DATETIME>20050613175830
ACCESSION NUMBER:		0001181431-05-034345
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20050609
FILED AS OF DATE:		20050613
DATE AS OF CHANGE:		20050613

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GREATER BAY BANCORP
		CENTRAL INDEX KEY:			0000775473
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		IRS NUMBER:				770387041
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1900 UNIVERSITY AVENUE, 6TH FLOOR
		CITY:			EAST PALO ALTO
		STATE:			CA
		ZIP:			94303
		BUSINESS PHONE:		4153751555

	MAIL ADDRESS:	
		STREET 1:		1900 UNIVERSITY AVENUE, 6TH FLOOR
		STREET 2:		420 COWPER ST
		CITY:			EAST PALO ALTO
		STATE:			CA
		ZIP:			943031504

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MID PENINSULA BANCORP
		DATE OF NAME CHANGE:	19941031

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SAN MATEO COUNTY BANCORP
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DE GROSZ FRED
		CENTRAL INDEX KEY:			0001189030

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-25034
		FILM NUMBER:		05893230

	BUSINESS ADDRESS:	
		STREET 1:		2860 W BAYSHORE RD
		CITY:			PALO ALTO
		STATE:			CA
		ZIP:			94303
		BUSINESS PHONE:		6508138200
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd82174.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-06-09</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000775473</issuerCik>
        <issuerName>GREATER BAY BANCORP</issuerName>
        <issuerTradingSymbol>GBBK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001189030</rptOwnerCik>
            <rptOwnerName>DE GROSZ FRED</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1900 UNIVERSITY AVENUE, 6TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>EAST PALO ALTO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94303</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO, ABD Insurance</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.67</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-06-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>47.875</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>16700</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>280731</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Convertible into common stock at 1.67 ratio.</footnote>
        <footnote id="F2">Immediately convertible.  No expiration date.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Frederick J. de Grosz</signatureName>
        <signatureDate>2005-06-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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