Oklahoma

001-13643

73-1520922

(State or other jurisdiction

(Commission

(IRS Employer

of incorporation)

File Number)

Identification No.)

Item 1.01

Entry into a Material Definitive Agreement

We adopted our Annual Officer Incentive Plan (the AOIP) in January 2000 and previously filed a copy of it with the Securities and Exchange Commission. The AOIP provides that certain of our officers may receive cash incentive awards based on their individual performance, and the performance and profitability of ONEOK, Inc. (the Company) and the performance of particular business units of the Company. The corporate and business unit criteria and individual performance criteria are established annually by the Executive Compensation Committee of our Board of Directors (the Committee). The Committee also establishes annual target awards for each officer.

On January 20, 2006, we filed with the Securities and Exchange Commission a current report on Form 8-K setting forth the corporate performance criteria for incentive awards under our AOIP for 2006.

On April 20, 2006, we revised the corporate performance criteria for incentive awards under the AOIP for 2006. The revised corporate performance criteria for 2006 provide that 50 percent of the performance measure under the AOIP is based on our return on invested capital (ROIC). Our actual ROIC for 2006 will be compared to the revised threshold, target and maximum levels. No incentive amount will be paid based on this performance measure if our actual ROIC for 2006 is below the revised threshold level. Also, the incentive payment based on our ROIC cannot exceed 300 percent of the target level set by the Committee, weighted at 50 percent.

The remaining 50 percent of the revised 2006 corporate performance measure is based on our earnings per share (EPS), adjusted to include minority interest and exclude the cumulative effect of accounting changes and certain gains or losses on sales of assets subsequent to our sale and transfer of assets to Northern Border Partners, L.P. Our actual EPS for 2006 will be compared to the revised threshold and target levels. No incentive amount will be paid based on this performance measure if the actual EPS for 2006 is below the revised threshold level. Also, the incentive payment based on EPS cannot exceed 100 percent of the targeted payment, weighted at 50 percent.

If both the revised maximum ROIC and the target EPS are achieved or exceeded, then the portion of a participant's total incentive award, based on the above-described corporate performance criteria, will be 200 percent of the officer's target award. After taking into account the achievement based on these corporate performance criteria, the Committee has the authority to adjust the amount of the award, based on business unit criteria and individual performance criteria.

2

ONEOK, Inc.

Date:

April 25, 2006

By:

/s/ Jim Kneale

Jim Kneale

Executive Vice President --

Finance and Administration

and Chief Financial Officer

(Principal Financial Officer)