| Subsidiaries | State of Incorporation or Organization | ||||
| Bighorn Gas Gathering, L.L.C. (49.0%) | Delaware | ||||
| Black Mesa Holdings, Inc. | Delaware | ||||
| Black Mesa Pipeline, Inc. | Delaware | ||||
| Black Mesa Pipeline Operations, L.L.C. | Delaware | ||||
| Black Mesa Technologies, Inc. | Oklahoma | ||||
| Border Midwestern Company | Delaware | ||||
| Chisholm Pipeline Company (50%) | Delaware | ||||
| Chisholm Pipeline Holdings, L.L.C. | Delaware | ||||
| Crestone Energy Ventures, L.L.C. | Delaware | ||||
| Crestone Gathering Services, L.L.C. | Delaware | ||||
| Crestone Powder River, L.L.C. | Delaware | ||||
| Crestone Wind River, L.L.C. | Delaware | ||||
| Fort Union Gas Gathering, L.L.C. (57.405%) | Delaware | ||||
| Guardian Pipeline, L.L.C. | Delaware | ||||
| Heartland Pipeline Company (general partnership) (50%) | Texas | ||||
| Lost Creek Gathering Company, L.L.C. (35%) | Delaware | ||||
| Mid Continent Market Center, L.L.C. | Kansas | ||||
| Midwestern Gas Transmission Company | Delaware | ||||
| Mont Belvieu I Fractionation Facility (joint venture) (80%) | Texas | ||||
| Northern Border Pipeline Company (general partnership) (50%) | Texas | ||||
| OkTex Pipeline Company, L.L.C. | Delaware | ||||
| ONEOK Arbuckle II Pipeline, L.L.C. | Oklahoma | ||||
| ONEOK Arbuckle North Pipeline, L.L.C. | Delaware | ||||
| ONEOK Arbuckle Pipeline, L.L.C. | Delaware | ||||
| ONEOK Bakken Pipeline, L.L.C. | Delaware | ||||
| ONEOK Bushton Processing, L.L.C. | Delaware | ||||
| ONEOK Elk Creek Pipeline, L.L.C. | Oklahoma | ||||
| ONEOK Energy Services Company, II | Delaware | ||||
| ONEOK Energy Services Company, L.P. | Texas | ||||
| ONEOK Energy Services Holdings, L.L.C. | Oklahoma | ||||
| ONEOK Field Services Company, L.L.C. | Oklahoma | ||||
| ONEOK Gas Storage Holdings, L.L.C. | Delaware | ||||
| ONEOK Gas Storage, L.L.C. | Oklahoma | ||||
| ONEOK Gas Transportation, L.L.C. | Oklahoma | ||||
| ONEOK Hydrocarbon GP, L.L.C. | Delaware | ||||
| ONEOK Hydrocarbon Holdings, L.L.C. | Delaware | ||||
| ONEOK Hydrocarbon Southwest, L.L.C. | Delaware | ||||
| ONEOK Hydrocarbon, L.L.C. | Delaware | ||||
| ONEOK Hydrocarbon, L.P. | Delaware | ||||
| ONEOK ILP GP, L.L.C. | Delaware | ||||
| ONEOK Leasing Company | Delaware | ||||
| ONEOK MB I, L.P. | Delaware | ||||
| ONEOK Midstream Gas Supply, L.L.C. | Oklahoma | ||||
| ONEOK Mont Belvieu Properties, L.L.C. | Delaware | ||||
| ONEOK Mont Belvieu Storage Company, L.L.C. | Delaware | ||||
| ONEOK NGL Gathering, L.L.C. | Delaware | ||||
| ONEOK NGL Pipeline, L.L.C. | Delaware | ||||
| ONEOK North System, L.L.C. | Delaware | ||||
| ONEOK Northern Border Pipeline Company Holdings, L.L.C. | Oklahoma | ||||
| ONEOK Overland Pass Holdings, L.L.C. | Oklahoma | ||||
| ONEOK Parking Company, L.L.C. | Delaware | ||||
| ONEOK Partners GP, L.L.C. | Delaware | ||||
| ONEOK Partners Intermediate Limited Partnership | Delaware | ||||
| ONEOK Partners, L.P. | Delaware | ||||
| ONEOK Permian NGL Operating Company, L.L.C. | Delaware | ||||
| ONEOK Pipeline Holdings, L.L.C. | Delaware | ||||
| ONEOK Rockies Investments, L.L.C. | Delaware | ||||
| ONEOK Rockies Midstream, L.L.C. | Delaware | ||||
| ONEOK Services Company, L.L.C. | Oklahoma | ||||
| ONEOK Southeast Texas NGL Pipeline, L.L.C. | Oklahoma | ||||
| ONEOK Sterling III Pipeline, L.L.C. | Oklahoma | ||||
| ONEOK Texas Gas Storage, L.L.C. | Texas | ||||
| ONEOK Underground Storage Company, L.L.C. | Kansas | ||||
| ONEOK Unit Holdings, Inc. | Delaware | ||||
| ONEOK VESCO Holdings, L.L.C. | Delaware | ||||
| ONEOK West Texas NGL Pipeline, L.L.C. | Texas | ||||
| ONEOK Western Trail Pipeline, L.L.C. | Oklahoma | ||||
| ONEOK WesTex Transmission, L.L.C. | Delaware | ||||
| Overland Pass Pipeline Company LLC (50%) | Delaware | ||||
| Roadrunner Gas Transmission Holdings, LLC (50%) | Delaware | ||||
| Roadrunner Gas Transmission, LLC (100% owned by Roadrunner Gas Transmission Holdings, LLC) | Delaware | ||||
| Venice Energy Services Company, L.L.C. (10.1765%) | Delaware | ||||
| Viking Gas Transmission Company | Delaware | ||||