May 5, 2017

Via EDGAR

Ms. Stephanie L. Sullivan

Senior Technical & Policy Advisor

US Securities and Exchange Commission

Division of Corporation Finance

100 F Street, NE

Washington, DC 20549

RE: BOK Financial Corporation

Form 10-K for the Fiscal Year Ended December 31, 2016

Filed February 28, 2017

File No. 001-37811

Dear Ms. Sullivan:

This letter confirms receipt of your comment letter dated April 28, 2017 regarding our Form 10-K for the fiscal year ended December 31, 2016. We will respond to your comments on or before June 2, 2017.

Please contact me at 918-588-6319 or John Morrow at 918-588-8673 if you have any questions.

Sincerely,

/s/ Steven E. Nell

Steven E. Nell

Executive Vice President

Chief Financial Officer

Cc: John C. Morrow, Chief Accounting Officer

Tamara Wagman, Frederic Dorwart, Lawyers