Exhibit 5.0


April 27, 2009

BOK Financial Corporation
Bank of Oklahoma Tower
P.O. Box 2300 Tulsa, OK 74192



Re:  BOK  Financial  Corporation  SEC  Registration  Statement  on Form S-8: BOK
     Financial Corporation (Trading Symbol "BOKF"):  Shares of BOKF Common Stock
     to be  Issued  Pursuant  to the  BOK  Financial  Corporation  2009  Omnibus
     Incentive Plan.


Ladies and Gentleman:

         I have acted as counsel to BOK Financial Corporation ("BOKF") in
connection with BOKF's Registration Statement on Form S-8 being filed on or
about April 28, 2009 with the Securities and Exchange Commission which respect
to the shares of Common Stock (the "Common Stock"), $0.00006 par value, of BOKF,
authorized for issuance under the BOK Financial Corporation 2009 Omnibus
Incentive Plan. I have reviewed BOKF's Registration Statement on Form S-8,
BOKF's Certificate of Corporation, BOKF's By-laws, and such corporate
proceedings of BOKF as I have deemed appropriate for purposes of rendering this
opinion. In my opinion, upon issuance of the shares of Common Stock pursuant to
the terms of the BOK Financial Corporation 2009 Omnibus Incentive Plan, such
shares will be duly and validly issued, fully paid and non-assessable. I hereby
consent to the filing of this opinion as an exhibit to the Registration
Statement.

                                                Sincerely,

                                            /s/ Frederic Dorwart

                                             Frederic Dorwart