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                                                                    EXHIBIT 99.4

                               OFFER TO EXCHANGE
                        7.75% NOTES DUE 2005, SERIES B,
                          FOR ANY AND ALL OUTSTANDING
                              7.75% NOTES DUE 2005
                                       OF
                                  ONEOK, INC.

To Our Clients:

     We are enclosing herewith a Prospectus dated                , 2000 (as
amended and supplemented from time to time, the "Prospectus") of ONEOK, Inc., an
Oklahoma corporation (the "Company"), and the related Letter of Transmittal (as
amended and supplemented from time to time, the "Letter of Transmittal") which
together constitute the offer of the Company (the "Exchange Offer") to exchange
$1,000 principal amount of its 7.75% Notes due 2005, Series B (the "Exchange
Notes"), registered under the Securities Act of 1933 (the "Securities Act"),
pursuant to a registration statement of which the Prospectus is a part, for each
$1,000 principal amount of its outstanding 7.75% Notes due 2005 (the "Old
Notes"), of which $350,000,000 aggregate principal amount is outstanding.

     PLEASE NOTE THAT THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY
TIME, ON                , 2000, UNLESS EXTENDED.

     The Exchange Offer is not conditioned upon any minimum number of Old Notes
being tendered.

     We are participants in the book-entry transfer facility of Old Notes held
by us for your account. A tender of such Old Notes can be made only by us as a
participant in the book-entry transfer facility and pursuant to your
instructions. The Letter of Transmittal is furnished to you for your information
only and cannot be used by you to tender Old Notes held by us for your account.

     We request instructions as to whether you wish to tender any or all of the
Old Notes held by us for your account pursuant to the terms and conditions of
the Exchange Offer. We also request that you confirm that we may on your behalf
make the representations contained in the Letter of Transmittal that are to be
made with respect to you as beneficial owner.

     Pursuant to the Letter of Transmittal, each holder will represent to the
Company that (i) neither the holder nor any other person receiving the Exchange
Notes is an "affiliate" of the Company within the meaning of Rule 405 under the
Securities Act, (ii) the holder is not a broker-dealer tendering Old Notes
acquired directly from the Company, (iii) the Exchange Notes are to be acquired
by the holder or the person receiving such Exchange Notes, whether or not such
person is the holder, in the ordinary course of business, (iv) the holder or any
such other person (other than a broker-dealer referred to in the next paragraph)
is not engaging, and does not intend to engage, in the distribution of the
Exchange Notes, (v) the holder or any such other person has no arrangement or
understanding with any person to participate in the distribution of the Exchange
Notes and (vi) the holder or any such other person acknowledges that if such
holder or any other person is deemed to have participated in the Exchange Offer
for the purpose of distributing the Exchange Notes, it must comply with the
registration and prospectus delivery requirements of the Securities Act in
connection with any resale of the Exchange Notes and cannot rely on the
interpretations by the staff of the Securities and Exchange Commission set forth
in certain no-action letters issued to third parties in similar transactions and
on which the Company is relying in making the Exchange Offer.

     Each participating broker-dealer that receives Exchange Notes for its own
account in exchange for Old Notes must acknowledge that it (i) acquired the Old
Notes for its own account as a result of market-making activities or other
trading activities, (ii) has not entered into any arrangement or understanding
with the Company or any "affiliate" of the Company (within the meaning of Rule
405 under the Securities Act) to distribute the Exchange Notes to be received in
the Exchange Offer and (iii) will deliver a prospectus meeting the requirements
of the Securities Act in connection with any resale of such Exchange Notes. By
acknowledging that it will deliver a prospectus meeting the requirements of the
Securities Act in connection with any resale of such Exchange Notes, such
broker-dealer will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act.

                                            Very truly yours,