Exhibit 21

BOK FINANCIAL CORPORATION

SUBSIDIARIES OF THE REGISTRANT

Banking Subsidiaries

BOKF, National Association (1)

CoBiz Bank (7)

Other subsidiaries of BOK Financial Corporation

BOK Capital Service Corporation

BOKC Real Estate Corporation (6)

BOKF Capital Corporation

BOKF-CC (Collision Works), LLC

BOKF-CC (FSE), LLC

BOKF-CC (Heartland), LLC

BOKF-CC (O2 Concepts), LLC

BOKF-CC (QRC), LLC

BOKF-CC (Switchgrass), LLC

BOKF Energy Fund Investment I, LLC

BOKF Equity, LLC

BOKF Private Equity Limited Partnership

BOKF Private Equity Limited Partnership II

BOK Financial Securities, Inc.

Cavanal Hill Distributors, Inc.

CoBiz IM, Inc. (7)

CoBiz Insurance, Inc. (7)

CoBiz Risk Management, Inc. (8)

CoBiz Wealth, LLC (7)

HFP II, LLC

The Milestone Group, Inc. (5)

RMA Holdings, Inc. (7)

Switchgrass I, LLC

Switchgrass II, LLC

Switchgrass III, LLC

Switchgrass IV, LLC

Switchgrass V, LLC

Switchgrass VI, LLC

Switchgrass Holdings, LLC

Switchgrass Management, LLC

Switchgrass Properties, LLC

Subsidiaries of BOKF, National Association(1)

Affiliated BancServices, Inc.

Affiliated Financial Holding Co.

Affiliated Financial Insurance Agency, Inc.

BancOklahoma Agri-Service Corporation

BOK Delaware, Inc. (3)

BOK Financial Asset Management, Inc. (2)

BOK Financial Equipment Finance, Inc.

BOK Funding Trust (3)

BOKFCDF Fund I, LLC

BOKF Community Development Fund, LLC

BOKF Community Development Fund II

BOKF Community Development Corporation

BOKF Petro Holding, LLC

BOKF Special Assets I, LLC

BOSC Agency, Inc. (Oklahoma)

BOSC Agency, Inc. (New Mexico) (4)

BOSC Agency, Inc. (Texas) (2)

Calicotte Ranch HOA, LLC

Cavanal Hill Investment Management, Inc.

Cottonwood Valley Ventures, Inc.

CVV Management, Inc.

CVV Partnership, an Oklahoma General Partnership

Oklahoma New Markets Fund I, LLC

Ottawa Land Partners, LLC (6)

Subsidiaries of CoBiz Bank(7)

AWREI, Inc.

CoBiz Public Finance Inc.

Western Real Estate Investors, Inc.

All Subsidiaries listed above were incorporated in Oklahoma, except as noted.

(1) Chartered by the United States Government

(2) Incorporated in Texas

(3) Incorporated in Delaware

(4) Incorporated in New Mexico

(5) Incorporated in Colorado

(6) Incorporated in Kansas

(7) Incorporated in Colorado

(8) Incorporated in Nevada