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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,
 Grh4p4qcG5g+uU41kYjb0FdqbfHffCVy+3ZxuhtLHjN9ESivi2I2EyLkdlJ9Ton2
 VA0fQUicbjKGkR5BznZfcg==

<SEC-DOCUMENT>0001104659-06-059235.txt : 20060901
<SEC-HEADER>0001104659-06-059235.hdr.sgml : 20060901
<ACCEPTANCE-DATETIME>20060901183403
ACCESSION NUMBER:		0001104659-06-059235
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060901
FILED AS OF DATE:		20060901
DATE AS OF CHANGE:		20060901

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			OLD SECOND BANCORP INC
		CENTRAL INDEX KEY:			0000357173
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				363143493
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		37 S RIVER ST
		CITY:			AURORA
		STATE:			IL
		ZIP:			60507
		BUSINESS PHONE:		7088920202

	MAIL ADDRESS:	
		STREET 1:		37 SOUTH RIVER STREET
		CITY:			AURORA
		STATE:			IL
		ZIP:			60507

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Krasner Mary e
		CENTRAL INDEX KEY:			0001374529

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-10537
		FILM NUMBER:		061072460

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		630-892-0202

	MAIL ADDRESS:	
		STREET 1:		37 S. RIVER ST.
		CITY:			AURORA
		STATE:			IL
		ZIP:			60506
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>a3.xml
<DESCRIPTION>3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2006-09-01</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000357173</issuerCik>
        <issuerName>OLD SECOND BANCORP INC</issuerName>
        <issuerTradingSymbol>OSBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001374529</rptOwnerCik>
            <rptOwnerName>Krasner Mary e</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>37 S. RIVER ST.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>AURORA</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60506</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>/s/ Mary E. Krasner</signatureName>
        <signatureDate>2006-09-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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