[Letterhead of Sandler O'Neill & Partners, L.P.]




                                                                  April 13, 2005

BY FACSIMILE AND EDGAR
- -----------------------

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, D.C.  20549

              Re:  BankFinancial Corporation. -
                   Registration Statement on Form S-1 (File No. 333-119217)
                   -------------------------------------------------------

Ladies and Gentlemen:

     In accordance  with Rule 461 under the  Securities Act of 1933, as amended,
we hereby join BankFinancial  Corporation (the "Company") in requesting that the
Company's  above-referenced  registration  statement  on  Form  S-1 be  declared
effective  on  April  15,  2005,  at 12:00  p.m.,  or as soon  thereafter  as is
practicable.

                                   Very truly yours,


                                   SANDLER O'NEILL & PARTNERS, L.P.
                                   By: Sandler O'Neill & Partners, Corp.,
                                        the sole general partner

                                      /s/ Michael Lacovara
                                      ----------------------------
                                          Michael Lacovara
                                          An Officer of the Company