SecProbe.io

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

       DIVISION OF
CORPORATION FINANCE
Mail Stop 4561
April 27, 2009

By U.S. Mail and Facsimile to: (630) 906-3208

J. Douglas Cheatham Executive Vice President and Chief Financial Officer Old Second Bancorp, Inc. 37 South River Street Aurora, Illinois 60507

Re: Old Second Bancorp, Inc.
Form 10-K for the Fiscal Year Ended December 31, 2008
(Filed March 16, 2009)
Form 8-K (Filed April 21, 2009)
 File No. 000-10537

Dear Mr. Cheatham:

We have reviewed your filing and have the following comments.  Where
indicated, we think you should re vise your document in response to these comments.  If
you disagree, we will consider your explanation as to why our comment is inapplicable or
a revision is unnecessary.  Please be as deta iled as necessary in your explanation.  In
some of our comments, we may ask you to provi de us with information so we may better
understand your disclosure.  After reviewing th is information, we may raise additional
comments.   Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.
 Form 10-K for the Fiscal Year Ended December 31, 2008

 Item 5.  Market for the Registrant’s Common Equity…, page 29

 1. It does not appear that the company included a perf ormance graph in its 2008
annual report to security holders.  Please  provide us with the performance graph
and confirm that the company will provide the performance graph to security holders in accordance with Item 201(e) of Regulation S-K in future filings.

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 2

Item 10. Directors, Executive Officers,  and Corporate Governance, page 32

2. Please revise to describe the business e xperience, including principal occupations
and employment, of Mr. Sloan during the past  five years.  Refer to Item 401(e) of
Regulation S-K.
 Item 11. Executive Compensation, page 32

 General

 3. You state that the sections in th e proxy statement marked “Executive
Compensation”, “Director Compensati on”, “Compensation Discussion and
Analysis” and “Compensation Committee Report” are furnished for the information of the Commission and are not deemed “filed” as part of the Form
10-K.  Other than the information required by Item 407(e)(5) of Regulation S-K, all of the information you reference is f iled, and not furnished.  Please file an
amendment to the Form 10-K confirming that these sections, other than the Compensation Committee Report, are incor porated into the Form 10-K and are
deemed filed, or provide the informati on required by Part III of Form 10-K.
Please also confirm that you will revi se your future filings accordingly.
 Compensation Discussion and Analysis, page 12 of Definitive Proxy Statement

 4. We note that the company benchmarks certain elements of compensation to its
peers.  Please identify, and revise future filings to disclose, the component companies that make up the compensation peer group(s) and the basis for selecting the peer group(s).  Refer to  Item 402(b)(2)(xiv) of Regulation S-K.
 Individual Goals Component, page 18 of Definitive Proxy Statement

 5. Please tell us why you have not disclose d certain of the performance targets
utilized in determining annual bonus compensation for your named executive
officers for the 2008 fiscal year.  For exam ple, you have not disclosed the specific
targets for return on equity, efficiency ra tio, total net charge-offs, net interest
margin and total loan growth that were used as bases for determining the individual component of the annual bonuses  for your named executive officers.
To the extent you believe that disclosure of the historical performance targets is
not required because it would result in competitive harm such that the targets
could be excluded under Instruction 4 to Item 402(b) of Regulation S-K, please
provide a detailed supplemental anal ysis supporting your conclusion.  In
particular, your competitive harm anal ysis should clearly explain the nexus
between disclosure of the performance objectives and the competitive harm that is likely to result from disclosure.  Refer to Item 402(b)(2)(v) of Regulation S-K and Regulation S-K Compliance and Disclosure Interpretation 118.04.

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 3

Item 13. Certain Relationships and Related Transactions…, page 33

 Transactions with Management, page 35 of Definitive Proxy Statement

 6. We note the disclosure on pages 35-36 of your definitive proxy statement that the
loans were made on substantially the same  terms as those prevailing at the time
for comparable transactions with other pers ons.  Please confirm, and revise future
filings to disclose, if true, that the loans were made on substantially the same terms, including interest rates and collate ral, as those prevailing at the time for
comparable loans with persons not related to the lender
.  Refer to Instruction 4(c)
to Item 404(a) of Regulation S-K.
 Signatures, page 36

 7. Please tell us if the report has been  signed by the company’s controller or
principal accounting officer.  Refer to Gene ral Instruction D(2)(a) to Form 10-K.
 Management’s Discussion and Analysis, page 48

 8. We note your disclosure that approxima tely $53.6 million of the problem loan
total was acquired through the Heritage Bank acquisition.  Further, we note you
carried over approximately $3.0 million of a llowance related to the loans acquired
from Heritage Bank.  Please tell us how  you considered whether any of the
acquired loans were within the scope of SOP 03-3 on the acquisition date.  To the
extent that you are accounting for so me of the acquired loans under SOP 03-3,
please revise your future filings to more clearly reflect that fact.
 Notes to Consolidated Financial Statements

 Note D: Securities, page 76

 9. We note the significant unrealized losses  related to your collateralized debt
obligations (backed by trust preferred s ecurities) at December 31, 2008.  We have
the following comments:

• Please provide us a detailed analysis of the securities’ impairment as of December 31, 2008 that identifies all avai lable evidence, explains the relative
significance of each piece of evidence, a nd identifies the primary evidence on
which you rely to support a realizable value equal to or greater than the
carrying value of the investment.  Speci fically tell us if  you considered all
available evidence, including informati on received after ye ar end, affecting
the projected cash flows as of the peri od end.  We may have further comment
based on your response.

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 4

• Please provide us with, and consider disclosing in future filings, a table
detailing the following information for these securities: deal name, single-
issuer or pooled, class, book value, fair  value, unrealized gain/loss, credit
ratings, number of banks in issuance, de ferrals and defaults as a dollar amount
and percentage of collatera l, and excess subordination.

10. We note the significant unrealized losses re lated to your investments in states and
political subdivisions.  Further, we no te your disclosure on page 27 that the
majority of your investments in tax-ex empt state and local municipalities are
insured by monoline insure rs, one of which was downgraded and two others
which were placed on rating review.  Pl ease tell us how you considered these
facts when determining no other than  temporary impairment existed on these
securities as of December 31, 2008.  Add itionally, tell us whether any of the
monoline insurers were downgraded subs equent to year e nd, and explain how
those downgrades (if any) were factored into your year end anal ysis.  Specify the
ratings of those insurers were “secure” or “vulnerable” as of December 31, 2008
and as of March 31, 2009.
 11. Please address the following regarding your  disclosure on page 67 regarding your
investment in stock of the Federal Ho me Loan Bank of Chicago, including your
statement that the stock is redeemable at par:

• Please revise your disclosures in future filings to discuss the regulatory order
issued to the FHLB Chicago that ge nerally requires approval prior to
redeeming or paying dividends on common stock.

• Please refer to paragraph 8(i) of SOP 01-6 and revise your future filings to
disclose your impairment policies for thes e investments.  Clearly disclose how
you determined this investment was not ot her than temporarily impaired as of
the balance sheet date.  Discuss the positive and negative factors you
considered, including the fact that the FHLB Chicago is subject to a
regulatory order that generally requires  approval prior to redeeming or paying
dividends on common stock, the fact th at they have had a significant amount
of losses prior to December 31, 2008, and that they had cumulative losses for the twelve months ended December 31, 2008.

• Provide us with your proposed future disclosure.

Note U: Fair Values of Financial Instruments, page 93

• We note you use a third-part y pricing agent, consensus pricing and dealer
quotes to value certain of your investment securities.  Please tell us and revise

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 5

your future filings to di sclose the following:

• The number of prices you generally obt ain per instrument, and if you obtained
multiple prices, how you determine the ultimate fair value used in your
financial statements;

• Whether, an if so, how and why, you adju sted prices obtained from the pricing
service; and
 • If true, please include an affirmative statement that based on your internal
review procedures, the fair values provided by the pricing services are
consistent with the principals of SFAS 157.

Form 8-K filed April 21, 2009

 Exhibit 99.1

 12. We note your presentation of “tangible capital to tangi ble assets” and “tangible
capital to risk-weighted assets.”   Thes e ratios appear to be  non-GAAP measures
as defined by Regulation G and Item 10(e) of Regulation S- K as they are not
required by GAAP, Commi ssion Rules, or banking regulatory requirements.  To
the extent you plan to provide these non-GAAP  ratios in the future, the staff notes
the following:

• To the extent these ratios are disclosed in future filings with the Commission,
you should comply with all of the requir ements in Item 10(e) of Regulation S-
K, including clearly labe ling the ratios as non-GAAP measures and complying
with all of the disclosure requirements.

• To the extent that you plan to disclose these ratios in future Item 2.02 Form 8-
Ks, you should provide all of the disclosures required by Item 10(e)(1)(i) of
Regulation S-K as required by Instructi on 2 to Item 2.02 of Form 8-K.

• To the extent you disclose or release publicly any material information that
includes a non-GAAP measure, you should be cognizant of the requirements in Regulation G to label the measure as non-GAAP and provide a reconciliation to the most clos ely comparable GAAP measure.

• As it relates to the presentation of risk we ighted assets, in future filings, please
generally disclose how risk weighted a ssets are calculated  under regulatory
capital rules and specifically state, if  true, that the nu mber disclosed is
calculated consistent with banking regulatory requirements.

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 6

Closing Comments

 As appropriate, please amend your filing and respond to these comments within
10 business days or tell us when you will provid e us with a response.  You may wish to
provide us with marked copies of the amendm ent to expedite our review.  Please furnish
a cover letter with your amendment that keys your responses to our comments and provides any requested information.  Detailed co ver letters greatly faci litate our review.
Please understand that we may have addi tional comments after reviewing your
amendment and responses to our comments.    We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.
  In connection with responding to our comments, please provide, in writing, a statement from the company acknowledging that:
• the company is responsible for the adequacy  and accuracy of the disclosure in the
filing;

• staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and
 • the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any person under the federal secu rities laws of the
United States.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.

J. Douglas Cheatham
Old Second Bancorp, Inc. April 27, 2009 Page 7

 You may contact Sharon Blume, Assist ant Chief Accountant, at (202) 551-3474
or Kevin Vaughn, Accounting Branch Chief, at (202) 551-3494 if you have questions
regarding comments on the fina ncial statements and relate d matters.  Please contact
Justin Dobbie at (202) 551-3469 or me at  (202) 551-3419 with any other questions

Sincerely,

Christian Windsor Special Counsel