EXHIBIT 99.1

                                 REVOCABLE PROXY

                           SOMONAUK FSB BANCORP, INC.

                         SPECIAL MEETING OF STOCKHOLDERS

      The undersigned hereby appoints [________________] and [_______________]
of Somonauk FSB Bancorp, Inc. ("Somonauk"), with full power of substitution, to
act as attorneys and proxies for the undersigned to vote all shares of common
stock of Somonauk that the undersigned is entitled to vote at Somonauk's Special
Meeting of Stockholders (the "Meeting"), to be held on [__________], 2005, at
[___________________________________], at [____] [__].m., local time, and any
and all adjournments and postponements thereof, as follows:

      1.    The adoption of the Agreement and Plan of Merger, dated as of
            February 22, 2005 (the "Merger Agreement"), among Princeton National
            Bancorp, Inc., Somonauk FSB Bancorp, Inc. and Somonauk Acquisition,
            Inc. and the approval of the transactions it contemplates

                   [ ] FOR            [ ] AGAINST        [ ] ABSTAIN

                 The Board of Directors recommends a vote "FOR"
              adoption of the Merger Agreement and the approval of
                       the transactions it contemplates.

      2.    The approval to adjourn the Meeting in the event that an
            insufficient number of shares is present in person or by proxy to
            adopt the Merger Agreement and approve the transactions it
            contemplates to permit further solicitation

                   [ ] FOR            [ ] AGAINST        [ ] ABSTAIN

      3.    In accordance with their discretion, upon all other matters that may
            properly come before said meeting and any adjournments or
            postponements of the meeting.

                (continued and to be signed on the reverse side)

      THIS PROXY WILL BE VOTED AS DIRECTED, BUT IF NO INSTRUCTIONS ARE
SPECIFIED, THIS PROXY WILL BE VOTED FOR ADOPTION OF THE MERGER AGREEMENT AND THE
APPROVAL OF THE TRANSACTIONS IT CONTEMPLATES. IF ANY OTHER BUSINESS IS PRESENTED
AT THE MEETING, THIS PROXY WILL BE VOTED BY THOSE NAMED IN THIS PROXY IN THEIR
BEST JUDGMENT. AT THE PRESENT TIME, THE BOARD OF DIRECTORS KNOWS OF NO OTHER
BUSINESS TO BE PRESENTED AT THE MEETING.

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           THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

      This proxy may be revoked at any time before it is voted by: (i) filing
with the Secretary of Somonauk at or before the Meeting a written notice of
revocation bearing a later date than this proxy; (ii) duly executing a
subsequent proxy relating to the same shares and delivering it to the Secretary
of Somonauk at or before the Meeting; or (iii) attending the Meeting and voting
in person (although attendance at the Meeting will not in and of itself
constitute revocation of this proxy). If this proxy is properly revoked as
described above, then the power of such attorneys and proxies shall be deemed
terminated and of no further force and effect.

      The undersigned acknowledges receipt from Somonauk, prior to the execution
of this proxy, of Notice of the Special Meeting and a Proxy
Statement-Prospectus.

      Date:______________, 2005               __________________________________
                                              PRINT NAME OF SHAREHOLDER

                                              __________________________________
                                              SIGNATURE OF SHAREHOLDER

                                              __________________________________
                                              PRINT NAME OF SHAREHOLDER

                                              __________________________________
                                              SIGNATURE OF SHAREHOLDER

                                    Please sign exactly as your name appears on
                                    this card. When signing as attorney,
                                    executor, administrator, trustee or
                                    guardian, please give your full title. If
                                    shares are held jointly, each holder should
                                    sign.

                  PLEASE PROMPTLY COMPLETE, DATE, SIGN AND MAIL
                THIS PROXY IN THE ENCLOSED POSTAGE-PAID ENVELOPE

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