November 16, 2009

Mr. John Nolan
Senior Chief Accountant
United States Securities and Exchange Commission
Division of Corporation Finance
100 F Street N.E.
Washington, DC 20549

Via EDGAR

Re:      BOK Financial Corporation
         Form 10-K for the Fiscal Year ended December 31, 2008
         Form 10-Q for the Quarterly Period ended March 31, 2009
         Form 10-Q for the Quarterly Period ended June 30, 2009
         File No. 0-19341

Dear Mr. Nolan:

This letter is submitted by BOK Financial Corporation ("the Company") in
response to comments received from the Securities and Exchange Commission staff
in a letter dated October 27, 2009 regarding the Company's filings referenced
above and supplements our previous response letter dated November 5, 2009. We
appreciate the staff's efforts to assist our compliance with applicable
disclosure requirements and to enhance disclosure in our filings.

Form 10-Q for the Quarterly Period Ended June 30, 2009

Management's  Discussion  and  Analysis of  Financial  Condition  and Results of
Operations

Net Loans Charged Off, page 60

Comment No. 4

4. The staff notes that the company had non-accruing commercial energy loans in
the amount of $47 million related to SemGroup Energy Partners, LP. The
disclosure states that this amount represents one-third of the company's
pre-bankruptcy amounts due from SemGroup. Please tell us how the company
determined the amount of non-accrual loans as well as the provisioning and
charge-offs to date related to these loans.

On June 30, 2008, the company's credit exposure before charge-offs and
write-downs to SemGroup Energy Partners, LP and related entities totaled $148
million consisting of a $46 million participation interest in a secured working
capital line of credit, a $4 million participation interest in a secured term
note and $98 million position for the fair value of various derivative contracts
due from SemGroup, net of cash margin held by the company. Derivative contracts
due to the company from SemGroup were secured positions pari passu with amount
due under the working capital line of credit.

On July 22, 2008, SemGroup and related entities filed for bankruptcy protection.
Our analysis of recoverability of amounts due from SemGroup was based on a
report (dated July 18, 2008) provided by The Blackstone Group, a consultant for
SemGroup and a borrowing base report (for May, 2008) prepared by SemGroup. These
reports, which were generally available to all participants in the credit,
estimated total secured debt outstanding of approximately $2.9 billion dollars
consisting of the working capital line of credit (including secured derivative
contracts) of $2.1 billion and term debt of $806 million. Based on these
reports, we estimated that projected cash flows available to satisfy secured
obligations totaled $1.9 billion, net of priority claims and costs and adjusted
for the timing of future cash flows consisting of $0.9 billion that supported
the working capital line of credit and $1.0 billion that supported the term
debt.

Our analysis concluded that the SemGroup loans were impaired (as defined by
Accounting Standards Codification 310-10-35-2) and that impairment loss could be
reasonably estimated which resulted in a $26 million charge-off of the working
capital line of credit in the second quarter of 2008. As substantially the
entire charge off amount was not previously reserved, we recognized a $26
million provision for loan losses in the same quarter. We classified the
remaining outstanding loan balances of $24 million as non-accruing at June 30,
2008 due to uncertainty of collecting all remaining amounts, including interest.

In addition, our analysis resulted in a $61 million charge to reduce the fair
value of derivative contracts to amounts we could reasonably expect to recover
from cash flows available to satisfy the secured obligations. This charge was
recognized against operating revenue in the second quarter of 2008.

During the third quarter of 2008, we received cash payment that further reduced
the fair value of the derivative contracts from $37 million to $30 million. We
also declared that an Early Termination Event (as defined by the ISDA) had
occurred which accelerated amounts due under the derivative contracts. As such,
the amounts due became secured borrowings as opposed to derivative instruments.
 Accordingly, we classified the remaining unpaid amounts due on derivative
contracts as an addition to non-accruing loans due from SemGroup. Our external
auditors, Ernst & Young, and our bank regulatory agency, the Office of the
Comptroller of the Currency, concurred with this classification. At September
30, 2008, our recorded investment in impaired loans to SemGroup was $48 million,
approximately one-third of the pre-bankruptcy amounts due from SemGroup.

Our recorded investment in amounts due from SemGroup has been reduced to $47
million at June 30, 2009 and $34 million at September 30, 2009 from the
application of cash proceeds received from sales of a portion of our claims
against the SemGroup bankruptcy estate. All cash proceeds received have been
applied as principal reductions.

We assess the recoverability of our recorded investment in amounts due from
SemGroup quarterly as part of our evaluation of the adequacy of the allowance
for loan losses. Based on our assessments, no additional charge-offs or
provision has been necessary.

We appreciate your continued efforts in assisting the Company with compliance
with applicable disclosure requirements and enhancement of disclosure in our
filings. Please contact me at 918-588-8673 if I can be of further assistance.

Sincerely,

BOK Financial Corporation

/s/ John C. Morrow
- -----------------------
John C. Morrow
Senior Vice President,
Chief Accounting Officer

cc:      Steven E. Nell, BOK Financial Corporation
         Tamara Wagman, Dorwart Lawyers
         Robert Kimbro, Ernst & Young