    <SEC-DOCUMENT>0000357173-17-000063-index.html : 20171227
    <SEC-HEADER>0000357173-17-000063.hdr.sgml : 20171227
    <ACCEPTANCE-DATETIME>20171226173812
    ACCESSION NUMBER:		0000357173-17-000063
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		9
    CONFORMED PERIOD OF REPORT:	20171226
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Other Events
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20171227
    DATE AS OF CHANGE:		20171226

    FILER:

    	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:			1215

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	000-10537
    		FILM NUMBER:		171274980

    	BUSINESS ADDRESS:
    		STREET 1:		37 S RIVER ST
    		CITY:			AURORA
    		STATE:			IL
    		ZIP:			60507
    		BUSINESS PHONE:		6308920202

    	MAIL ADDRESS:
    		STREET 1:		37 SOUTH RIVER STREET
    		CITY:			AURORA
    		STATE:			IL
    		ZIP:			60507
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>osbc-20171226x8k.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: osbc-20171226x8k.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>2
    <FILENAME>osbc-20171226ex991073737.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 2 - file: osbc-20171226ex991073737.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.2
    <SEQUENCE>3
    <FILENAME>osbc-20171226ex9929a6a20.htm
    <DESCRIPTION>EX-99.2
    <TEXT>
    Document 3 - file: osbc-20171226ex9929a6a20.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>4
    <FILENAME>osbc20171226ex991073737001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 4 - file: osbc20171226ex991073737001.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>5
    <FILENAME>osbc20171226ex9929a6a20001.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 5 - file: osbc20171226ex9929a6a20001.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>6
    <FILENAME>osbc20171226ex9929a6a20002.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 6 - file: osbc20171226ex9929a6a20002.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>osbc20171226ex9929a6a20003.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: osbc20171226ex9929a6a20003.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>osbc20171226ex9929a6a20004.gif
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 8 - file: osbc20171226ex9929a6a20004.gif

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>osbc20171226x8k001.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: osbc20171226x8k001.jpg

    </DOCUMENT>
    </SEC-DOCUMENT>