ONEOK INC /NEW/, 424B5, 2000-04-19

ONEOK INC /NEW/
424B5, 2000-04-19
NATURAL GAS TRANSMISISON & DISTRIBUTION

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<PAGE>
FILED PURSUANT TO RULE NO. 424(b)(5)
REGISTRATION NO. 333-76375

Prospectus Supplement
April 19, 2000
(To prospectus dated April 19, 2000)

$240,000,000

[ONEOK LOGO]
ONEOK, INC.

Floating Rate Notes Due April 24, 2002

The Company: . Delivery: We expect that delivery
of the notes will be made to
. We engage in several aspects of investors on or about April 24,
the energy business. We purchase, 2000. The notes will be issued
gather, compress, transport, store only in book-entry form through
and distribute natural gas; lease the facilities of the DTC.
pipeline capacity to others; drill
for and produce oil and gas; and
sell natural gas liquids. We also The Notes:
engage in gas marketing and, to a
limited extent, wholesale . Maturity: April 24, 2002.
marketing of electricity. As a
regulated natural gas utility, we . Interest: The per annum rate of
distribute natural gas to interest for the notes will equal
approximately 1.4 million three-month LIBOR, reset
customers in the states of quarterly, plus 65 basis points
Oklahoma and Kansas. (.65%).

. In April 2000, we acquired certain . Interest Payments: Quarterly in
gathering and processing assets, cash in arrears on each
marketing and trading operations January 24, April 24, July 24 and
and storage and transmission October 24, commencing on July 24,
pipelines from Kinder Morgan, Inc. 2000, and at maturity.
for approximately $109 million,
subject to an adjustment for . Redemption: The notes will not be
working capital of approximately redeemable prior to maturity.
$53 million.
. Ranking: The notes rank equally
. In March 2000, we acquired certain with all of our other unsecured
processing plants and gas and unsubordinated indebtedness.
gathering and transmission
pipelines from Dynegy Inc. for
approximately $308 million. Proposed Trading Format:

. In January 2000, we elected to . The notes will not be listed on
terminate our proposed merger with any securities exchange or
Southwest Gas Corporation. We are included in any automated
parties to a number of pending quotation system.
lawsuits relating to the
previously proposed merger.

The Offering:

. We intend to use the net proceeds
from the offering to repay
outstanding indebtedness.

<TABLE>
<CAPTION>
Price to Discounts and Proceeds to
Public Commissions ONEOK
------------ ------------- ------------
<S> <C> <C> <C>
Per Floating Rate Note.................. 100.0% 0.3% 99.7%
Total................................... $240,000,000 $720,000 $239,280,000
</TABLE>

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or determined if
this prospectus supplement or the attached prospectus is truthful or complete.
Any representation to the contrary is a criminal offense.

Banc of America Securities LLC

Banc One Capital Markets, Inc.

Chase Securities Inc.

Salomon Smith Barney Inc.
<PAGE>

TABLE OF CONTENTS

Prospectus Supplement

<TABLE>
<CAPTION>
Page
----
<S> <C>
About ONEOK................................................................ S-3
Cautionary Statement Concerning Forward-looking Statements................. S-4
Use of Proceeds............................................................ S-5
Capitalization............................................................. S-5
Ratio of Earnings to Fixed Charges......................................... S-5
Description of Notes....................................................... S-6
Underwriting............................................................... S-10
Experts.................................................................... S-11
Legal Matters.............................................................. S-11

Prospectus

About this Prospectus...................................................... 2
Where You Can Find More Information........................................ 2
Forward-looking Information................................................ 3
About ONEOK................................................................ 4
Use of Proceeds............................................................ 4
Ratio of Earnings to Fixed Charges......................................... 5
Description of Debt Securities............................................. 5
Plan of Distribution....................................................... 13
Legal Matters.............................................................. 14
Experts.................................................................... 14
</TABLE>

We have not, and the underwriters have not, authorized any other person to
provide you with any information or to make any representations not contained
in this prospectus supplement or the attached prospectus. If anyone provides
you with different or inconsistent information, you should not rely on it. We
are not, and the underwriters are not, making an offer of any securities other
than the notes. This prospectus supplement is part of, and you must read it in
addition to, the attached prospectus dated April 19, 2000. You should assume
that the information appearing in this prospectus supplement and the attached
prospectus, as well as the information incorporated by reference, is accurate
as of the date on the front cover of this prospectus supplement only.

The distribution of this prospectus supplement and the attached prospectus,
and the offering of the notes, may be restricted by law in certain
jurisdictions. You should inform yourself about, and observe, any of these
restrictions. This prospectus supplement and the attached prospectus do not
constitute, and may not be used in connection with, an offer or solicitation by
anyone in any jurisdiction in which the offer or solicitation is not
authorized, or in which the person making the offer or solicitation is not
qualified to do so, or to any person to whom it is unlawful to make the offer
or solicitation.

S-2
<PAGE>

ABOUT ONEOK

General

ONEOK and its subsidiaries engage in several aspects of the energy business.
We purchase, gather, compress, transport and store natural gas for distribution
to consumers. We transport gas for others and lease pipeline capacity to others
for use in transporting gas. We drill for and produce gas and oil, and extract
and sell natural gas liquids. We also engage in the natural gas marketing
business and, to a limited extent, wholesale marketing of electricity. As a
regulated natural gas utility, we distribute natural gas to approximately 1.4
million customers in the states of Oklahoma and Kansas.

Recent Developments

Acquisition of Assets and Operations from Kinder Morgan. On April 5, 2000,
we consummated the acquisition of gathering and processing assets located in
Oklahoma, Kansas and West Texas from Kinder Morgan, Inc. We also acquired
Kinder Morgan's marketing and trading operations, as well as some storage and
transmission pipelines in the mid-continent region. We paid approximately $109
million for these assets subject to an adjustment for working capital of
approximately $53 million. We also assumed liabilities related to an operating
lease for a processing plant for which we anticipate we will establish a
liability for uneconomic lease obligation terms and some firm capacity lease
obligations to third parties for which we anticipate we will establish a
liability for out-of-market terms of those obligations. The acquired assets and
operations include over 12,000 miles of gas gathering and transmission pipeline
systems, six gas processing plants with capacity of 1.3 billion cubic feet per
day and 10.5 billion cubic feet of natural gas storage capacity.

Acquisition of Assets from Dynegy. On March 22, 2000, we consummated the
acquisition of eight gas processing plants, interests in two other gas
processing plants and approximately 7,000 miles of gas gathering and
transmission pipeline systems in Oklahoma, Kansas and Texas from Dynegy Inc. We
paid approximately $308 million for these assets. The current throughput of the
assets is approximately 240 million cubic feet per day with an approximate
capacity of 375 million cubic feet per day. Production of natural gas liquids
from the assets averages 25,000 barrels per day.

Southwest Gas Transaction. In April 1999, we announced an agreement to
acquire Southwest Gas Corporation by merger for cash consideration of
approximately $917 million, plus the assumption of approximately $900 million
of related indebtedness. On January 18, 2000, we were notified by Southwest Gas
that it believed we had breached the merger agreement. Southwest Gas demanded
that the alleged breach be cured. On January 20, 2000, our board of directors
voted to terminate the merger agreement. On January 21, 2000, we advised
Southwest Gas that we did not believe we were in breach of the merger agreement
and that we had exercised our right to terminate the merger agreement. On the
same date, we filed a complaint in the U.S. District Court in Tulsa, Oklahoma
seeking a declaratory judgment that we had properly terminated the merger
agreement. On January 24, 2000, in response to our termination of the merger
agreement, Southwest Gas filed a complaint against ONEOK and Southern Union
Company in the U.S. District Court in Phoenix, Arizona. Southern Union, which
had attempted to acquire Southwest Gas, is a party or intervenor in various
actions and previously pending regulatory proceedings relating to our
previously proposed merger with Southwest Gas. These actions and proceedings
are described in detail in the documents incorporated by reference in this
prospectus, as are two shareholder derivative class actions also related to the
previously proposed merger that were filed in the District Court of Tulsa
County, Oklahoma on February 3, 2000 against our board of directors. See "Where
You Can Find More Information" in the accompanying prospectus.

We have denied any liability or breach with regard to the merger agreement
and the various actions and proceedings referred to above and in the documents
incorporated by reference in this prospectus. Nevertheless, we expect that
these actions and proceedings will continue for the foreseeable future. These
actions and proceedings are at a preliminary stage and, thus, it is not
possible to predict their outcome. If the complainants

S-3
<PAGE>

in any of the actions or proceedings were to be successful in their claims
against us and if substantial damages were to be awarded, our financial
condition, cash flow and results of operations could be materially affected. We
intend to continue to vigorously defend these claims.

CAUTIONARY STATEMENT CONCERNING FORWARD-LOOKING STATEMENTS

Some of the statements contained and incorporated in this prospectus
supplement and the accompanying prospectus are forward-looking statements
within the meaning of the Private Securities Litigation Reform Act of 1995. The
forward-looking statements relate to anticipated financial performance,
management's plans and objectives for future operations, business prospects,
outcome of regulatory proceedings, market conditions, the timing of the
consummation of the proposed merger and other matters. The Private Securities
Litigation Reform Act of 1995 provides a safe harbor for forward-looking
statements in certain circumstances. The following discussion is intended to
identify important factors that could cause future outcomes to differ
materially from those set forth in the forward-looking statements.

Forward-looking statements include the information concerning possible or
assumed future results of our operations and other statements contained or
incorporated in this prospectus supplement or the accompanying prospectus
identified by words such as "anticipate," "estimate," "expect," "intend,"
"believe," "projection" or "goal."

You should not place undue reliance on the forward-looking statements. They
are based on known and unknown risks, uncertainties and other factors that may
cause our actual results, performance or achievements to be materially
different from any future results, performance or achievements expressed or
implied by the forward-looking statements. Those factors may affect our
operations, markets, products, services and prices. In addition to any
assumptions and other factors referred to specifically in connection with the
forward-looking statements, factors that could cause our actual results to
differ materially from those contemplated in any forward-looking statement
include, among others, the following:

. the effects of weather and other natural phenomena on sales and prices;

. increased competition from other energy suppliers as well as alternative
forms of energy;

. the capital intensive nature of our business;

. further deregulation, or "unbundling," of the natural gas business;

. competitive changes in the natural gas gathering, transportation and
storage business resulting from deregulation, or "unbundling," of the
natural gas business;

. the profitability of assets or businesses acquired by us;

. risks of hedging and marketing activities as a result of changes in
energy prices;

. economic climate and growth in the geographic areas in which we do
business;

. the uncertainty of gas and oil reserve estimates;

. the timing and extent of changes in commodity prices for natural gas,
electricity, crude oil and liquified petroleum gas;

. the effects of changes in governmental policies and regulatory actions,
including income taxes, environmental compliance and authorized rates;

. the results of litigation relating to our previously proposed acquisition
of Southwest Gas Corporation or to the termination of our merger
agreement with Southwest Gas; and

. the other factors listed in the reports we have filed and may file with
the Securities and Exchange Commission, which are incorporated by
reference.

S-4
<PAGE>

actual results to differ materially from those projected. We have no obligation
and make no undertaking to update publicly or revise any forward-looking
statements.

USE OF PROCEEDS

We estimate that we will receive net proceeds from the sale of the notes
offered by us, after deducting estimated offering expenses of approximately
$250.0 thousand and underwriting discounts and commissions payable by us, of
approximately $239.3 million. We intend to use all of the net proceeds from the
sale of the notes to refinance short-term indebtedness incurred in March and
April 2000 to fund the Dynegy and Kinder Morgan acquisitions. The weighted
average annual interest rate of this short-term indebtedness is 6.11%.

CAPITALIZATION

The following table sets forth our capitalization as of February 29, 2000,
our pro forma capitalization giving effect to the issuance on March 1, 2000 of
$350.0 million principal amount of our 7.75% Notes due 2005, the proceeds of
which were applied to refinance short-term notes payable, and our pro forma
capitalization as adjusted to reflect the issuance of the notes. The following
data is qualified in its entirety by reference to, and should be read together
with, the detailed information and financial statements appearing in the
documents incorporated in this prospectus supplement and the accompanying
prospectus.

<TABLE>
<CAPTION>
As of February 29, 2000
----------------------------------------------
Pro Forma
Actual Pro Forma As Adjusted
-------------- -------------- --------------
(dollars in millions)
<S> <C> <C> <C> <C> <C> <C>
Notes.......................... $ -- -- % $ -- -- % $ 240.0 9.5%
7.75% Notes due 2005........... -- -- 349.4 15.3 349.4 13.8
Other long-term debt (excluding
current portion).............. 772.6 39.9 772.6 33.8 772.6 30.6
Convertible preferred stock.... 564.4 29.1 564.4 24.6 564.4 22.3
Common shareholders' equity.... 601.6 31.0 601.6 26.3 601.6 23.8
-------- ----- -------- ----- -------- -----
Total capitalization......... $1,938.6 100.0% $2,288.0 100.0% $2,528.0 100.0%
======== ===== ======== ===== ======== =====
Short-term notes payable
(including current portion of
long-term debt)............... $ 365.1 $ 18.1 $ 0.0
======== ======== ========
</TABLE>

RATIO OF EARNINGS TO FIXED CHARGES

Our ratio of earnings to fixed charges for each of the periods shown is as
follows:

<TABLE>
<CAPTION>
For the Four Months Ended For the Years Ended August 31,
------------------------- ----------------------------------------------------
December 31, 1999 1999 1998 1997 1996 1995
------------------------- ------ ------ ------ ------ ------
<S> <C> <C> <C> <C> <C>
2.94 x 4.06 x 5.50 x 3.51 x 3.28 x 2.70 x
</TABLE>

We have computed the ratios of earnings to fixed charges by dividing
earnings by fixed charges. For this purpose, "earnings" consists of net income
plus fixed charges and income taxes, less undistributed income from equity
investees. "Fixed charges" consists of interest charges, amortization of debt
discounts and issue costs and the representative interest portion of operating
leases.

S-5
<PAGE>

DESCRIPTION OF NOTES

General

The notes will be issued under the Indenture dated as of September 24, 1998,
as amended and supplemented, that we entered into with Chase Bank of Texas,
National Association, as trustee. Whenever particular defined terms of the
Indenture are referred to, those defined terms are incorporated herein by
reference.

The notes will be issued only in fully registered form, without coupons, in
denominations of $1,000 and integral multiples thereof. The notes will be
represented by a permanent global note registered in the name of The Depository
Trust Company or its nominees. Payment of principal and interest will be made
in immediately available funds to the registered holder, which will be DTC or
its nominee.

The notes will mature on April 24, 2002. We are not permitted to redeem the
notes prior to maturity. We will have the right to issue additional debt
securities, including additional notes, under the Indenture at any time,
without limit. The notes will be our unsecured and unsubordinated obligations.
The notes will not be listed for trading on any exchange.

Interest

The notes will bear interest at a rate per annum, reset quarterly, equal to
three-month LIBOR plus 65 basis points (.65%). The calculation agent will
determine the interest rate for the notes. Interest will be computed on the
basis of a 360-day year and the actual number of days in the applicable
Interest Period (as defined below). Interest is payable quarterly on each
January 24, April 24, July 24 and October 24, commencing July 24, 2000, and at
maturity. Interest is payable for the period commencing on and including the
immediately preceding interest payment date and ending on and including the day
preceding the next interest payment date (an "Interest Period"), with the
exception that the first Interest Period will commence on and include April 24,
2000. We will pay interest to the persons in whose names the notes are
registered at the close of business on the fifteenth calendar day prior to the
interest payment date. However, interest that we pay at maturity will be
payable to the person to whom the principal will be payable.

If any interest payment date for the notes, other than at maturity, would
otherwise be a day that is not a Business Day (as defined below), the interest
payment date will be postponed to the next day that is a Business Day. If the
maturity date falls on a day that is not a Business Day, payment of principal
and interest will be paid on the next succeeding Business Day with the same
force and effect as if made on that date and no interest on the payment will
accrue from and after that date.

The interest rate for each Interest Period will be determined by Bank of
America, N.A. as calculation agent in accordance with the following provisions:

The per annum rate of interest for each Interest Period will be three-month
LIBOR as determined on the second Banking Day (as defined below) preceding the
relevant Interest Reset Date (as defined below) for the Interest Period (the
"Interest Determination Date") plus the applicable spread described above. The
Interest Determination Date for the first Interest Period will be April 19,
2000. "LIBOR" for each Interest Period will be determined by the calculation
agent in accordance with the following provisions:

(1) On each Interest Determination Date, the calculation agent will
determine LIBOR as the offered rate for three-month deposits in U.S.
dollars in the London interbank market, which appears on Telerate Page
3750 as of 11:00 a.m., London time, on the Interest Determination Date.

(2) If the rate does not appear on Telerate Page 3750, or if Telerate Page
3750 is unavailable, the calculation agent will request each of four
major reference banks in the London interbank market to provide the
calculation agent with its offered quotation, expressed as a rate per
annum, for three-

S-6
<PAGE>

month deposits in U.S. dollars to leading banks in the London interbank
market at approximately 11:00 a.m., London time, on the Interest
Determination Date, in a principal amount of not less than $1,000,000,
that is representative for a single transaction in U.S. dollars in that
market at that time. If at least two quotations from the major reference
banks are provided, LIBOR in respect of the Interest Determination Date
will be the arithmetic mean of those quotations.

(3) If less than two of the major reference banks in the London interbank
market provide the calculation agent with the offered quotations, LIBOR
in respect of that Interest Determination Date will be the arithmetic
mean of the rates quoted by three major banks in New York City selected
by the calculation agent, at approximately 11:00 a.m., New York City
time, on that Interest Determination Date for three-month loans in U.S.
dollars to leading European banks, in a principal amount equal to an
amount of not less than $1,000,000, that is representative for a single
transaction in that market at that time.

(4) If the major banks in New York City selected by the calculation agent
are not quoting as described in clause (3), LIBOR will be LIBOR as
determined on the prior Interest Determination Date.

"Banking Day" means any day, other than a Saturday or Sunday, on which
commercial banks are open for business, including dealings in U.S. dollars, in
London and that is a Business Day.

"Business Day" means any day, other than a Saturday or Sunday, on which
banking institutions in New York City are open for business.

"Interest Reset Date" means, with respect to any Interest Period, the first
day of such Interest Period.

"Telerate Page 3750" means the display designated on the Dow Jones Telerate
Service, or any successor service, as page "3750", or any other page as may
replace that page on that service, or any successor service, for the purpose of
displaying the LIBOR Index on a daily basis.

All percentages resulting from any calculation on the notes will be rounded,
if necessary, to the nearest one hundred-thousandth of a percentage point, with
five one-millionths of a percentage point rounded upward (e.g., 9.876545% (or
.09876545) being rounded to 9.87655% (or .0987655)), and dollar amounts used in
or resulting from such calculations will be rounded to the nearest cent, with
one-half cent rounded upward.

We have agreed that, so long as any of the notes remain outstanding, we will
maintain under appointment a calculation agent to calculate the rate of
interest payable on the notes. The calculation agent's calculation of the rate
of interest payable on the notes will be conclusive and binding on us and the
holders of the notes, absent manifest error. If the calculation agent is unable
or unwilling to continue to act as calculation agent, or if the calculation
agent fails to establish the applicable rate of interest for any Interest
Period, or if we remove the calculation agent, we will appoint another bank to
act as the calculation agent. The calculation agent, however, cannot resign or
be removed until acceptance of an appointment by a successor as evidenced by an
appropriate agreement entered into between us and the successor calculation
agent.

Book-Entry Only--The Depository Trust Company

DTC will act as the initial securities depositary for the notes. The notes
will be issued only as fully registered securities registered in the name of
Cede & Co., DTC's nominee. One or more fully registered global note
certificates will be issued, representing in the aggregate the total principal
amount of notes, and will be deposited with DTC.

DTC is a limited-purpose trust company organized under the New York Banking
Law, a "banking organization" within the meaning of the New York Banking Law, a
member of the Federal Reserve System, a "clearing corporation" within the
meaning of the New York Uniform Commercial Code and a "clearing agency"
registered pursuant to the provisions of Section 17A of the Exchange Act. DTC
holds securities that

S-7
<PAGE>

its participants deposit with DTC. DTC also facilitates the settlement among
its participants of securities transactions, such as transfers and pledges, in
deposited securities through electronic computerized book-entry changes in its
participant's accounts, thereby eliminating the need for physical movement of
securities certificates. DTC's direct participants include securities brokers
and dealers, banks, trust companies, clearing corporations and other
organizations. DTC is owned by a number of its direct participants and by the
New York Stock Exchange, Inc., the American Stock Exchange, Inc. and the
National Association of Securities Dealers, Inc. Access to the DTC system is
also available to others such as securities brokers and dealers, banks and
trust companies that clear through or maintain a custodial relationship with a
direct participant, either directly or indirectly as an indirect participant.
The rules applicable to DTC and its participants are on file with the
Securities and Exchange Commission.

Purchases of notes within the DTC system must be made by or through direct
participants, which will receive a credit for the notes on DTC's records. The
ownership interest of each actual purchaser of notes (the purchaser, or the
person to whom that purchaser conveys his or her ownership interest, a
"beneficial owner") is in turn to be recorded on the direct and indirect
participants' records. Beneficial owners will not receive written confirmation
from DTC of their purchases, but beneficial owners are expected to receive
written confirmations providing details of the transactions, as well as
periodic statements of their holdings, from the direct or indirect participants
through which the beneficial owners purchased notes. Transfers of ownership
interests in the notes are to be accomplished by entries made on the books of
participants acting on behalf of beneficial owners. Beneficial owners will not
receive certificates representing their ownership interests in notes, except if
use of the book-entry system for the notes is discontinued or we determine that
beneficial owners may exchange their ownership interests for certificates or
there shall have occurred an event of default under the Indenture.

DTC has no knowledge of the actual beneficial owners of the notes. DTC's
records reflect only the identity of the direct participants to whose accounts
the notes are credited, which may or may not be the beneficial owners. The
participants will remain responsible for keeping account of their holdings on
behalf of their customers.

Conveyance of notices and other communications by DTC to direct
participants, by direct participants to indirect participants and by direct
participants and indirect participants to beneficial owners will be governed by
arrangements among them, subject to any statutory or regulatory requirements as
may be in effect from time to time.

We will send redemption notices to DTC. If less than all of the notes are
being redeemed, DTC will reduce the amount of the interest of each direct
participant in the notes in accordance with its procedures.

Although voting with respect to the notes is limited, in those cases where a
vote is required, neither DTC nor Cede & Co. will itself consent or vote with
respect to the notes. Under its usual procedures, DTC would mail an omnibus
proxy to us as soon as possible after the record date. The omnibus proxy
assigns Cede & Co.'s consenting or voting rights to those direct participants
to whose accounts the notes are credited on the record date (identified in a
listing attached to the omnibus proxy).

Payments on the notes will be made to DTC. DTC's practice is to credit
direct participants' accounts on the relevant payment date in accordance with
their respective holdings shown on DTC's records unless DTC has reason to
believe that it will not receive payments on that payment date. Payments by
participants to beneficial owners will be governed by standing instructions and
customary practices, as is the case with securities held for the account of
customers registered in "street name," and will be the responsibility of the
participant and not of DTC or us, subject to any statutory or regulatory
requirements as may be in effect from time to time. Payment to DTC is our
responsibility, disbursements of those payments to direct participants is the
responsibility of DTC and disbursements of those payments to the beneficial
owners is the responsibility of direct and indirect participants.

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<PAGE>

Except as provided herein, a beneficial owner of an interest in a global
note will not be entitled to receive physical delivery of notes. Accordingly,
each beneficial owner must rely on the procedures of DTC to exercise any rights
under the notes. The laws of some jurisdictions may require that purchasers of
securities take physical delivery of securities in definitive form. Those laws
may impair the ability to transfer beneficial interests in a global note.

DTC may discontinue providing its services as security depositary with
respect to the notes at any time by giving us reasonable notice. Under those
circumstances, in the event that a successor securities depositary is not
obtained, certificates representing the notes will be printed and delivered to
the holders of record. Additionally, we may decide to discontinue use of the
system of book-entry transfers through DTC (or a successor depositary) with
respect to the notes. In that event, certificates for the notes will be printed
and delivered to the holders of record.

The information in this section concerning DTC and DTC's book-entry system
has been obtained from sources that we believe to be reliable, but we take no
responsibility for the accuracy thereof. We have no responsibility for the
performance by DTC or its participants of their respective obligations as
described herein or under the rules and procedures governing their respective
operations.

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<PAGE>

UNDERWRITING

Subject to the terms and conditions set forth in an underwriting agreement
dated April 18, 2000, among us and the underwriters named below, we have agreed
to sell to each of the underwriters and each of the underwriters severally has
agreed to purchase from us the principal amount of the notes set forth opposite
its name below. The underwriting agreement provides that the obligations of the
underwriters are subject to certain conditions and that the underwriters will
be obligated to purchase all of the notes if any are purchased.

<TABLE>
<CAPTION>
Principal
Amount of
Underwriter Notes
----------- ------------
<S> <C>
Banc of America Securities LLC.............................. $168,000,000
Banc One Capital Markets, Inc............................... 24,000,000
Chase Securities Inc........................................ 24,000,000
Salomon Smith Barney Inc.................................... 24,000,000
------------
Total................................................... $240,000,000
============
</TABLE>

The underwriters have advised us that they propose initially to offer the
notes to the public at the offering price set forth on the cover page of this
prospectus supplement. After the initial public offering, the public offering
price may be changed. We will compensate the underwriters by selling the notes
to them at a price that is less than the price set forth on the cover page of
this prospectus supplement by the amount of the "discount" equal to 0.30% of
the principal amount. The underwriters may sell notes to some dealers at a
price less a concession not in excess of 0.20% of the principal amount. The
underwriters may allow, and those dealers may reallow, a concession not in
excess of 0.16% of the principal amount.

The notes are a new issue of securities with no established trading market.
We do not intend to apply for listing of the notes on any national securities
exchange or for quotation of the notes on any automated dealer quotation
system. The underwriters have advised us that they intend to make a market in
the notes after the offering, although they are under no obligation to do so.
The underwriters may discontinue any market-making activities at any time
without any notice. We can give no assurance as to the liquidity of the trading
market for the notes or that a public trading market for the notes will
develop. If no active public trading market develops, the market price and
liquidity of the notes may be adversely affected. If the notes are traded, they
may trade at a discount from their initial offering price, depending on factors
such as prevailing interest rates, the market for similar securities, the
performance of our company as well as other factors not listed here.

The underwriters, as well as dealers and agents, may purchase and sell notes
in the open market. These transactions may include stabilizing transactions and
purchases to cover syndicate short positions created in connection with the
offering. Stabilizing transactions consist of bids and purchases made to
prevent or slow a decline in the market price of the notes. Syndicate short
positions arise when the underwriters or agents sell more notes than we are
required to sell to them in the offering. The underwriters may also impose
penalty bids whereby the underwriting syndicate may reclaim selling concessions
allowed either syndicate members or broker dealers who sell notes in the
offering for their own account if the syndicate repurchases the notes in
stabilizing or covering transactions. These activities may stabilize, maintain
or otherwise affect the market price of the notes, which may be higher as a
result of these activities than it might otherwise be in the open market. These
activities, if commenced, may be discontinued at any time without notice.

We and the underwriters make no representation or prediction as to the
direction or magnitude of any effect that the transactions described in the
preceding two paragraphs may have on the price of the notes. In addition, we
and the underwriters make no representation that the underwriters will engage
in those types of transactions or that those transactions, once commenced, will
not be discontinued without notice.

We have agreed to indemnify the underwriters against, or to contribute to
payments that the underwriters may be required to make with respect to, certain
liabilities, including liabilities under the Securities Act of 1933.

S-10
<PAGE>

Each of the underwriters and certain of their affiliates have provided, and
may continue to provide, investment banking, financial advisory, commercial
banking and other services to us and our affiliates. In addition, Chase Bank of
Texas, National Association, the trustee for the notes, is an affiliate of
Chase Securities Inc.

EXPERTS

The consolidated financial statements of ONEOK and its subsidiaries as of
August 31, 1999 and 1998, and for each of the years in the three-year period
ended August 31, 1999 have been incorporated by reference herein in reliance
upon the report of KPMG LLP, independent certified public accountants,
incorporated by reference herein, and upon the authority of said firm as
experts in accounting and auditing.

LEGAL MATTERS

Various legal matters, including the validity of the notes, will be passed
on for ONEOK by Gable & Gotwals, Tulsa, Oklahoma. Various legal matters
relating to the offering will be passed on for the underwriters by Jones, Day,
Reavis & Pogue, Chicago, Illinois. Jones, Day, Reavis & Pogue will rely on
Gable & Gotwals as to matters of Oklahoma law. Jones, Day, Reavis & Pogue from
time to time acts as counsel to ONEOK.

S-11
<PAGE>

$540,000,000

ONEOK, Inc.

Debt Securities

----------------

We may offer from time to time unsecured Debt Securities, which may be
senior notes or debentures or other unsecured evidences of indebtedness in one
or more series. The aggregate initial offering price of the Debt Securities
that are offered will not exceed $540,000,000. We will offer the Debt
Securities in an amount and on terms to be determined by market conditions at
the time of the offering.

We will provide specific terms of the particular Debt Securities being
offered in supplements to this prospectus. You should read this prospectus and
any supplement carefully before you invest. This prospectus may not be used to
sell Debt Securities unless accompanied by a prospectus supplement.

----------------

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
adequacy or accuracy of this prospectus. Any representation to the contrary is
a criminal offense.

----------------

The date of this Prospectus is April 19, 2000.
<PAGE>

TABLE OF CONTENTS

<TABLE>
<S> <C>
About this Prospectus....................................................... 2
Where You Can Find More Information......................................... 2
Forward-looking Information................................................. 3
About ONEOK................................................................. 4
Use of Proceeds............................................................. 4
Ratio of Earnings to Fixed Charges.......................................... 5
Description of Debt Securities.............................................. 5
Plan of Distribution........................................................ 13
Legal Matters............................................................... 14
Experts..................................................................... 14
</TABLE>

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that ONEOK ("we" or
"ONEOK") filed with the Securities and Exchange Commission using a "shelf"
registration process. Using this process, we may offer the Debt Securities
described in this prospectus in one or more offerings with a total initial
offering price of up to $540,000,000. This prospectus provides you with a
general description of the Debt Securities we may offer. Each time we offer
Debt Securities, we will provide you a prospectus supplement and any pricing
supplement that will contain information about the specific terms of that
particular offering. The prospectus supplement or pricing supplement may also
add, update or change information contained in this prospectus. To obtain
additional information that may be important to you, you should read the
exhibits filed by us with this registration statement or our other filings with
the Securities and Exchange Commission. You also should read this prospectus
and any prospectus supplement or pricing supplement together with the
additional information described under the heading "Where You Can Find More
Information."

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and special reports, proxy statements and other
information with the Securities and Exchange Commission. You can read and copy
any materials we file with the Securities and Exchange Commission at its Public
Reference Room at 450 Fifth Street, N.W., Washington, D.C. 20549 and at its
regional offices located at Seven World Trade Center, New York, New York 10048
and at 500 West Madison Street, Chicago, Illinois 60661. You can obtain
information about the operations of the Securities and Exchange Commission
Public Reference Room by calling the Securities and Exchange Commission at 1-
800-SEC-0330. The Securities and Exchange Commission also maintains a Web site
that contains information we file electronically with the Securities and
Exchange Commission, which you can access over the Internet at
http://www.sec.gov. Our common stock is listed on the New York Stock Exchange
(NYSE: OKE), and you can obtain information about us at the offices of the New
York Stock Exchange, 20 Broad Street, New York, New York 10005.

This prospectus is part of a registration statement we have filed with the
Securities and Exchange Commission relating to the Debt Securities. As
permitted by Securities and Exchange Commission rules, this prospectus does not
contain all of the information we have included in the registration statement
and the accompanying exhibits we file with the Securities and Exchange
Commission. You may refer to the registration statement and the exhibits for
more information about us and the Debt Securities. The registration statement
and the exhibits are available at the Securities and Exchange Commission's
Public Reference Room or through its Web site.

2
<PAGE>

The Securities and Exchange Commission allows us to "incorporate by
reference" the information we file with it, which means that we can disclose
important information to you by referring you to those documents. The
information we incorporate by reference is an important part of this
prospectus, and later information that we file with the Securities and Exchange
Commission will automatically update and supersede some of this information. We
incorporate by reference the documents listed below, and any future filings we
make with the Securities and Exchange Commission under Section 13(a), 13(c), 14
or 15(d) of the Securities Exchange Act of 1934 until we sell all the Debt
Securities. The documents we incorporate by reference are:

. our annual report on Form 10-K for the year ended August 31, 1999;

. our reports on Form 10-Q for the quarterly period ended November 30, 1999
and the transition period ended December 31, 1999; and

. our current reports on Form 8-K dated October 14, 1999, October 21, 1999,
November 8, 1999, December 15, 1999, January 7, 2000, January 24, 2000,
January 27, 2000, February 1, 2000, February 9, 2000, February 22, 2000,
March 21, 2000, March 28, 2000, April 4, 2000 and April 6, 2000.

You may request a copy of these filings (other than an exhibit to the
filings unless we have specifically incorporated that exhibit by reference into
the filing), at no cost, by writing or telephoning us at the following address:

ONEOK, Inc.
100 West Fifth Street
Tulsa, Oklahoma 74103
Attention: Chief Financial Officer
Telephone: (918) 588-7000

You should rely only on the information incorporated by reference or
provided in this prospectus or any prospectus supplement. We have not
authorized anyone else to provide you with different information. We may only
use this prospectus to sell Debt Securities if it is accompanied by a
prospectus supplement. We are only offering these Debt Securities in states
where the offer is permitted. You should not assume that the information in
this prospectus or any applicable prospectus supplement is accurate as of any
date other than the date on the front of those documents.

FORWARD-LOOKING INFORMATION

Some of the statements contained and incorporated in this prospectus are
forward-looking statements within the meaning of the Private Securities
Litigation Reform Act of 1995. The forward-looking statements relate to
anticipated financial performance, management's plans and objectives for future
operations, business prospects, outcome of regulatory proceedings, market
conditions and other matters. The Private Securities Litigation Reform Act of
1995 provides a safe harbor for forward-looking statements in various
circumstances. The following discussion is intended to identify important
factors that could cause future outcomes to differ materially from those set
forth in the forward-looking statements.

Forward-looking statements include the items identified in the preceding
paragraph, the information concerning possible or assumed future results of
operations and other statements contained or incorporated in this prospectus
identified by words such as "anticipate," "estimate," "expect," "intend,"
"believe," "projection" or "goal."

3
<PAGE>

addition to any assumptions and other factors referred to specifically in
connection with the forward-looking statements, factors that could cause our
actual results to differ materially from those contemplated in any forward-
looking statement include, among others, the following:

. the effects of weather and other natural phenomena on sales and prices;

. increased competition from other energy suppliers as well as alternative
forms of energy;

. the capital intensive nature of our business;

. further deregulation, or "unbundling," of the natural gas business;

. competitive changes in the natural gas gathering, transportation and
storage business resulting from deregulation, or "unbundling," of the
natural gas business;

. the profitability of assets or businesses acquired by us;

. risks of hedging and marketing activities as a result of changes in
energy prices;

. economic climate and growth in the geographic areas in which we do
business;

. the uncertainty of gas and oil reserve estimates;

. the timing and extent of changes in commodity prices for natural gas,
electricity, crude oil and liquified petroleum gas;

. the effects of changes in governmental policies and regulatory actions,
including income taxes, environmental compliance and authorized rates;

. the results of litigation relating to our previously proposed acquisition
of Southwest Gas Corporation or to the termination of our merger
agreement with Southwest Gas; and

. the other factors listed in the reports we have filed and may file with
the Securities and Exchange Commission, which are incorporated by
reference.

Other factors and assumptions not identified above were also involved in the
making of the forward-looking statements. The failure of those assumptions to
be realized, as well as other factors, may also cause actual results to differ
materially from those projected. We have no obligation and make no undertaking
to update publicly or revise any forward-looking statements.

ABOUT ONEOK

USE OF PROCEEDS

Unless we inform you otherwise in the prospectus supplement, we will use the
net proceeds from the sale of the Debt Securities offered by this prospectus
for general corporate purposes. These purposes may include repayment and
refinancing of debt, acquisitions, working capital, capital expenditures and
repurchases and redemptions of securities. Pending any specific application, we
may initially invest funds in short-term marketable securities or apply them to
the reduction of short-term indebtedness.

4
<PAGE>

RATIO OF EARNINGS TO FIXED CHARGES

Our ratio of earnings to fixed charges for each of the periods shown is as
follows:

<TABLE>
<CAPTION>
For the Four Months Ended For the Years Ended August 31,
- ------------------------- -----------------------------------------------------------------
December 31, 1999 1999 1998 1997 1996 1995
- ------------------------- ----- ----- ----- ----- -----
<S> <C> <C> <C> <C> <C>
2.94x 4.06x 5.50x 3.51x 3.28x 2.70x
</TABLE>

DESCRIPTION OF DEBT SECURITIES

The following description states the general terms and provisions of our
unsecured Debt Securities. In this prospectus, "Debt Securities" means the
debentures, notes, bonds and other evidences of indebtedness that we will issue
under an Indenture that we entered into with Chase Bank of Texas, National
Association, as Trustee, on September 24, 1998. Each prospectus supplement that
we provide when we offer Debt Securities will describe the specific terms of
the Debt Securities offered through that prospectus supplement and any general
terms outlined in this section that will not apply to those Debt Securities.

We have summarized the material terms and provisions of the Indenture in
this section. The summary is not complete. We have filed the form of the
Indenture as an exhibit to this registration statement. You should read the
form of Indenture for additional information before you buy any Debt
Securities. The Indenture is qualified under the Trust Indenture Act of 1939.
You should refer to the Trust Indenture Act for provisions that apply to the
Debt Securities. This summary also is subject to and qualified by reference to
the description of the particular terms of the Debt Securities described in the
applicable prospectus supplement or supplements and pricing supplement or
supplements. Capitalized terms used but not defined in this summary have the
meanings specified in the Indenture.

The Debt Securities will be our unsecured obligations and will rank equally
with any of our other senior, unsecured debt. Debt Securities issued under the
Indenture will be issued as part of a series that has been established pursuant
to a supplemental indenture or other corporate action designating the specific
terms of the series of Debt Securities. A prospectus supplement will describe
these terms and will include, among other things, the following:

. the title of the Debt Securities of the particular series;

. the total principal amount of those Debt Securities and the percentage of
their principal amount at which we will issue those Debt Securities;

. the date or dates on which the principal of those Debt Securities will be
payable;

. the interest rate, the method for determining the interest rate (if the
interest rate is variable), the date from which interest will accrue,
interest payment dates and record dates for interest payments;

. the place or places where payments on those Debt Securities will be made,
where holders may surrender their Debt Securities for transfer or
exchange and where to serve notices or demands;

. any provisions for optional redemption or early repayment;

. any provisions that would obligate us to redeem, purchase or repay those
Debt Securities;

. whether payments on the Debt Securities of the particular series will be
payable by reference to any index, formula or other method;

5
<PAGE>

. any deletions from, changes of or additions to the events of default or
covenants described in this prospectus;

. the portion of the principal amount of those Debt Securities that will be
payable if the maturity is accelerated, if other than the entire
principal amount;

. any additional means of defeasance of all or any portion of those Debt
Securities, any additional conditions or limitations to defeasance of
those Debt Securities or any changes to those conditions or limitations;

. any provisions granting special rights to holders of the Debt Securities
of the particular series upon the occurrence of events identified in the
prospectus supplement;

. if other than the trustee, the designation of any paying agent or
security registrar for those Debt Securities; and the designation of any
transfer or other agents or depositories for those Debt Securities;

. whether we will issue the Debt Securities of the particular series in
individual certificates to each holder or in the form of temporary or
permanent global securities that a depository will hold on behalf of
holders;

. the denominations in which we will issue the Debt Securities of the
particular series or in which they may be owned, if other than $1,000 or
any integral multiple of $1,000;

. whether and in what circumstances any additional amounts may be payable
on those Debt Securities to foreign holders; and

. any other terms or conditions that are consistent with the Indenture.

We may sell the Debt Securities at a discount (which may be substantial)
below their stated principal amount. These discounted Debt Securities may bear
no interest or interest at a rate that at the time of issuance is below market
rates. We will describe in the prospectus supplement any material United States
federal income tax consequences and other special considerations.

Restrictive Covenants

We have agreed to two principal restrictions on our activities for the
benefit of holders of the Debt Securities. The restrictive covenants summarized
below will apply to a series of Debt Securities (unless waived or amended) as
long as any of those Debt Securities are outstanding, unless the prospectus
supplement for the series states otherwise. We have used in this summary
description capitalized terms that we have defined below under "--Glossary." In
this description of the covenants only, all references to "us" or "we" mean
ONEOK and our principal subsidiaries, unless the context clearly indicates
otherwise. Our principal subsidiaries are those that own or lease a Principal
Property.

Other than the restrictions on Liens and Sale/Leaseback transactions
described below, the Indenture and the Debt Securities do not contain any
covenants or other provisions designed to protect holders of any Debt
Securities in the event we participate in a highly leveraged transaction. The
Indenture and the Debt Securities also do not contain provisions that give
holders of the Debt Securities the right to require us to repurchase their
securities in the event of change-in-control, recapitalization or similar
restructuring or otherwise or upon a decline in our credit rating.

For these purposes, "debt" includes all notes, bonds, debentures or similar
evidences of obligations for borrowed money.

Limitation on Liens

We have agreed that we will issue, assume or guarantee debt for borrowed
money secured by any Lien upon a Principal Property or shares of stock or debt
of any principal subsidiary only if we secure the Debt Securities equally and
ratably with or prior to the debt secured by that Lien. If we secure the Debt
Securities in

6
<PAGE>

this manner, we have the option to secure any of our other debt or obligations
equally and ratably with or prior to the debt secured by the Lien and,
accordingly, equally and ratably with the Debt Securities. This covenant has
exceptions that permit:

. Liens that existed on September 29, 1998, the date we first issued a
series of Debt Securities;

. Liens on any Principal Property or shares of stock or debt of any entity
that constitutes a principal subsidiary existing at the time we merge or
consolidate with that entity or acquire its property or at the time the
entity becomes a principal subsidiary;

. Liens on any Principal Property existing at the time we acquire that
Principal Property so long as the Lien does not extend to any of our
other Principal Property;

. Liens on any Principal Property, and any Lien on the shares of stock of
any principal subsidiary formed for the purpose of acquiring that
Principal Property, either:

. securing all or part of the cost of acquiring, constructing,
improving, developing or expanding the Principal Property that was
incurred before, at or within 12 months after the latest of the
acquisition or completion of the assets or their commencing
commercial operation; or

. securing debt to finance the purchase price of the Principal Property
or the cost of constructing, improving, developing or expanding the
assets that was incurred before, at or within 12 months after the
latest of the acquisition or completion of the assets or their
commencing commercial operation;

. Liens on any Principal Property or shares of stock or debt of any
principal subsidiary to secure debt owed to us;

. Liens securing industrial development, pollution control or other revenue
bonds of a government entity;

. Liens arising in connection with a project financed with, and securing,
Non-Recourse Indebtedness;

. statutory or other Liens arising in the ordinary course of business and
relating to amounts that are not delinquent or remain payable without
penalty or that we are contesting in good faith;

. Liens (other than Liens imposed by the Employee Retirement Income
Security Act of 1974) on our property incurred or required in connection
with workmen's compensation, unemployment insurance and other social
security legislation;

. Liens securing taxes that remain payable without penalty or that we are
contesting in good faith if we believe we have adequate reserves for the
taxes in question;

. rights that any governmental entity may have to purchase or order the
sale of any of our property upon payment of reasonable compensation;

. rights that any governmental entity may have to terminate any of our
franchises, licenses or other rights or to regulate our property and
business;

. Liens that we do not assume or on which we do not customarily pay
interest and that exist on real estate or other rights we acquire for
sub-station, measuring station, regulating station, gas purification
station, compressor station, transmission line, distribution line or
right-of-way purposes;

. easements or reservations in our property for roads, pipelines, gas
transmission and distribution lines, electric light and power
transmission and distribution lines, water mains and other similar
purposes and zoning ordinances, regulations and restrictions that do not
impair the use of the property in the operation of our business; and

. any extensions, renewals, substitutions or replacements of the above-
described Liens or any debt secured by these Liens if both:

. the amount of debt secured by the new Lien and not otherwise
permitted does not exceed the principal amount of debt so secured at
the time of the renewal or refunding; and

. the new Lien is limited to the property (plus any improvements)
secured by the original Lien.

7
<PAGE>

In addition, without securing the Debt Securities as described above, we may
issue, assume or guarantee debt that the Lien covenant would otherwise restrict
in a total principal amount that, when added to all of our other outstanding
debt that the Lien covenant would otherwise restrict and the total amount of
Attributable Debt outstanding for Sale/Leaseback Transactions, does not exceed
a "basket" equal to 15% of Consolidated Net Tangible Assets. When calculating
this total principal amount, we exclude from the calculation Attributable Debt
from Sale/Leaseback Transactions in connection with which we have purchased
property or retired debt as described below under "--Limitation on
Sale/Leaseback Transactions."

Limitation on Sale/Leaseback Transactions

We have agreed that we will enter into a Sale/Leaseback Transaction only if
at least one of the following applies:

. we could incur debt secured by a Lien on the Principal Property that is
the subject of that Sale/Leaseback Transaction;

. the Attributable Debt subject to that Sale/Leaseback Transaction would be
in an amount permitted under the "basket" described above under "--
Limitation on Liens";

. the proceeds of that Sale/Leaseback Transaction are used for our business
and operations; or

. within the period ending 12 months after the closing of the
Sale/Leaseback Transaction, we apply the net proceeds of the
Sale/Leaseback Transaction to the voluntary retirement of any Debt
Securities issued under the Indenture or Funded Indebtedness (other than
Funded Indebtedness that we hold or that is subordinate in right of
payment to any Debt Securities issued under the Indenture).

Glossary

"Attributable Debt" means, as to any particular lease under which any Person
is at the time liable, at any date as of which the amount thereof is to be
determined, the total net amount of rent required to be paid by that Person
under the lease during the remaining term thereof (excluding amounts required
to be paid on account of maintenance and repairs, services, insurance, taxes,
assessments, water rates and similar charges and contingent rents), discounted
from the respective due dates thereof at the weighted average of the rates of
interest (or yield to maturity, in the case of Debt Securities originally sold
at a discount) borne by the Debt Securities then outstanding under the
Indenture, compounded annually.

"Consolidated Net Tangible Assets" means (1) the total amount of assets
(less applicable reserves and other properly deductible items) which under
generally accepted accounting principles, or GAAP, would be included on a
consolidated balance sheet of ours and our subsidiaries after deducting
therefrom (A) all current liabilities, provided, however, that there will not
be deducted billings recorded as revenues deferred pending the outcome of rate
proceedings (less applicable income taxes thereon), if and to the extent the
obligation to refund the same has not been finally determined, (B) appropriate
allowance for minority interests in common stocks of subsidiaries and (C) all
goodwill, trade names, trademarks, patents, unamortized debt discount and
expense and other like intangibles, which in each case under GAAP would be
included on the consolidated balance sheet, less (2) the amount which would be
so included on the consolidated balance sheet for investments (less applicable
reserves) made in subsidiaries.

"Funded Indebtedness" as applied to any Person, means all debt of that
Person maturing after, or renewable or extendible at that Person's option
beyond, 12 months from the date of determination.

"Lien" means any lien, mortgage, pledge, encumbrance, charge or security
interest securing debt; provided, however, that the following types of
transactions will not be considered for purposes of this definition to result
in a Lien: (1) any acquisition by us of any property or assets subject to any
reservation or exception under the terms of which any vendor, lessor or
assignor creates, reserves or excepts or has created, reserved or excepted an
interest in oil, gas or any other mineral in place or the proceeds thereof, (2)
any conveyance or

8
<PAGE>

assignment whereby we convey or assign to any Person or Persons an interest in
oil, gas or any other mineral in place or the proceeds thereof, (3) any Lien
upon any property or assets either owned or leased by us or in which we own an
interest that secures for the benefit of the Person or Persons paying the
expenses of developing or conducting operations for the recovery, storage,
transportation or sale of the mineral resources of the property or assets (or
property or assets with which it is unitized) the payment to that Person or
Persons of our proportionate part of the development or operating expenses or
(4) any hedging arrangements entered into in the ordinary course of business,
including any obligation to deliver any mineral, commodity or asset in
connection with the arrangement.

"Non-Recourse Indebtedness" means, at any time, debt incurred after the date
of the Indenture by us in connection with the acquisition of property or assets
by us or the financing of the construction of or improvements on property,
whenever acquired, provided that, under the terms of that debt and pursuant to
applicable law, the recourse at that time and thereafter of the lenders with
respect to the debt is limited to the property or assets so acquired, or the
construction or improvements, including debt as to which a performance or
completion guarantee or similar undertaking was initially applicable to the
debt or the related property or assets if the guarantee or similar undertaking
has been satisfied and is no longer in effect.

"Person" means any individual, corporation, partnership, limited liability
company, joint venture, association, joint-stock company, trust, unincorporated
organization or government or any agency or political subdivision thereof.

"Principal Property" means any property located in the United States, except
any property that in the opinion of our board of directors is not of material
importance to the total business conducted by us and our consolidated
subsidiaries.

"Sale/Leaseback Transaction" means any arrangement with any Person pursuant
to which we lease any Principal Property that has been or is to be sold or
transferred by us to that Person, other than (1) a lease for a term, including
renewals at the option of the lessee, of not more than three years or
classified as an operating lease under generally accepted accounting
principles, (2) leases between us and one of our principal subsidiaries or
between principal subsidiaries, (3) leases of a Principal Property executed by
the time of, or within 12 months after the latest of, the acquisition, the
completion of construction or improvement, or the commencement of commercial
operation, of the Principal Property and (4) the ground lease for ONEOK Plaza,
100 West Fifth Street, Tulsa, Oklahoma 74103.

Consolidation, Merger and Sale of Assets

The Indenture generally permits a consolidation or merger between us and
another entity. It also permits the sale by us of all or substantially all of
our assets. We have agreed, however, that we will consolidate with or merge
into any entity or transfer or dispose of all or substantially all of our
assets to any entity only if:

. immediately after giving effect to the transaction, no default or event
of default would have occurred and be continuing or would result from the
transaction;

. we are the continuing corporation or, if we are not the continuing
corporation, the resulting entity is organized and existing under the
laws of any United States jurisdiction and assumes the due and punctual
payments on the Debt Securities and the performance of our covenants and
obligations under the Indenture and those Debt Securities; and

. we provide the trustee with a certificate and a legal opinion, each
stating that the Indenture permits the transaction.

If we engage in any of these transactions that result in any Principal
Property or shares of stock or debt of any principal subsidiary becoming
subject to any Lien and unless we are otherwise able to create that Lien, the
Indenture provides that the Debt Securities (so long as those Debt Securities
are entitled to the protection of the "Limitation on Liens" covenant) will be
secured to at least the same extent as the debt that would become secured by
the Lien as a result of the transaction.

9
<PAGE>

Events of Default

Unless we inform you otherwise in the prospectus supplement, the following
are events of default for a series of Debt Securities:

. our failure to pay interest on that series of Debt Securities for 30 days
after it becomes due and payable;

. our failure to pay principal of or any premium on that series of Debt
Securities when due;

. our failure to comply with any of our covenants or agreements for that
series of Debt Securities or in the Indenture (other than an agreement or
covenant that we have included in the Indenture solely for the benefit of
less than all series of Debt Securities) for 60 days after the trustee or
the holders of at least 25% in principal amount of all outstanding Debt
Securities affected by that failure provide written notice to us;

. the default under any agreement under which we or any subsidiary that
owns or leases Principal Property have at the time outstanding debt in
excess of $15,000,000 and, if that debt has not already matured, it has
been accelerated and the acceleration is not rescinded within 30 days
after we receive notice from the trustee or the holders of at least 25%
in principal amount of all outstanding Debt Securities of a series so
long as, prior to the entry of judgment in favor of the trustee for
payment of the Debt Securities of that series, we do not cure the
default, or the default under the agreement has not been waived;

. various events involving our bankruptcy, insolvency or reorganization; or

. any other event of default provided for that series of Debt Securities.

A default under one series of Debt Securities will not necessarily be a
default under another series. The trustee may withhold notice to the holders of
a series of Debt Securities of any default or event of default (except in any
payment on that series of Debt Securities) if the trustee considers it in the
interest of the holders of that series of Debt Securities to do so.

If an event of default for any series of Debt Securities occurs and is
continuing, the trustee or the holders of at least 25% in principal amount of
the outstanding Debt Securities of the series affected by the default (or, in
some cases, 25% in principal amount of all Debt Securities affected, voting as
one class) may require us to pay on an accelerated basis the principal of and
all accrued and unpaid interest on those Debt Securities. The holders of a
majority in principal amount of the outstanding Debt Securities of the series
affected by the default (or of all Debt Securities affected, voting as one
class) may in some cases rescind this accelerated payment requirement.

If an event of default occurs and is continuing, the trustee must use the
degree of care and skill of a prudent man in the conduct of his own affairs.
The trustee will become obligated to exercise any of its powers under the
Indenture at the request of any of the holders of any Debt Securities only
after those holders have offered the trustee indemnity reasonably satisfactory
to it.

The holders of a majority in principal amount of Debt Securities of any
series have the right to waive past defaults under the Indenture that relate to
that series except for a default in the payment on the Debt Securities or a
provision that can only, under the Indenture, be modified or amended if all
holders that are affected consent.

In most cases, holders of a majority in principal amount of the outstanding
Debt Securities of a series (or of all Debt Securities affected, voting as one
class) may direct the time, method and place of:

. conducting any proceeding for any remedy available to the trustee; and

. exercising any trust or power conferred on the trustee.

The Indenture requires us to file each year with the trustee a written
statement as to our compliance with the covenants contained in the Indenture.

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<PAGE>

Modification and Waiver

We may amend or supplement the Indenture if the holders of a majority in
principal amount of the outstanding Debt Securities of all series that the
amendment or supplement affects (acting as one class) consent to it. Without
the consent of the holder of each Debt Security affected, however, no
modification may:

. reduce the principal of the Debt Security or change its stated maturity;

. reduce the rate of or change the time for payment of interest on the Debt
Security;

. reduce any premium payable on the redemption of the Debt Security or
change the time at which the Debt Security may or must be redeemed;

. change any obligation to pay additional amounts on the Debt Security;

. impair the holder's right to institute suit for the enforcement of any
payment on the Debt Security;

. impair the holder's right to convert or exchange any Debt Security;

. reduce the percentage of principal amount of Debt Securities whose
holders must consent to an amendment to or supplement of the Indenture;

. reduce the percentage of principal amount of Debt Securities necessary to
waive compliance with some of the provisions of the Indenture; or

. modify provisions relating to amendment or waiver, except to increase
percentages or to provide that other provisions of the Indenture cannot
be amended or waived without the consent of each holder affected.

We may amend or supplement the Indenture or waive any provision of it
without the consent of any holders of Debt Securities in various circumstances,
including:

. to provide for the assumption of our obligations under the Indenture and
the Debt Securities by a successor;

. to add covenants that would benefit the holders of any Debt Securities or
to surrender any of our rights or powers;

. to provide for the issuance of additional securities, including Debt
Securities of a particular series, under the Indenture

. to add events of default;

. to provide any security for or guarantees of any series of Debt
Securities;

. to provide for the form or terms of any series of Debt Securities;

. to appoint a successor trustee or to provide for the administration of
the trusts under the Indenture by more than one trustee;

. to cure any ambiguity, omission, defect or inconsistency that does not
adversely affect the interests of the holders of outstanding Debt
Securities of any series;

. to make any change to the extent necessary to permit or facilitate
defeasance or discharge of any series of Debt Securities that does not
adversely affect the interests of the holders of outstanding Debt
Securities of any series; or

. to make any change that does not affect the rights of any holder.

The holders of a majority in principal amount of the outstanding Debt
Securities may waive our obligations to comply with various covenants,
including those relating to:

. our obligation to secure the Debt Securities in the event of mergers,
consolidations and sales of assets;

. corporate existence; and

. the restrictions on Liens and Sale/Leaseback Transactions.

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Defeasance

When we use the term defeasance, we mean discharge from some or all of our
obligations under the Indenture. If we deposit with the trustee funds or
government securities the maturing principal and interest of which is
sufficient to make payments on the Debt Securities of a series on the dates
those payments are due and payable, then, at our option, either of the
following will occur:

. "legal defeasance," which means that we will be discharged from our
obligations with respect to the Debt Securities of that series; or

. "covenant defeasance," which means that we will no longer have any
obligation to comply with the restrictive covenants under the Indenture
and any other restrictive covenants that apply to that series of the Debt
Securities, and the related events of default will no longer apply to us.

If we defease a series of Debt Securities, the holders of the Debt
Securities of the series affected will not be entitled to the benefits of the
Indenture, except for our obligations to pay additional amounts, if any, to
provide temporary Debt Securities, to register the transfer or exchange of Debt
Securities, to replace stolen, lost or mutilated Debt Securities or to maintain
paying agencies and hold moneys for payment in trust. In the case of covenant
defeasance, our obligation to pay principal, premium and interest on the Debt
Securities will also survive.

Unless we inform you otherwise in the prospectus supplement, we will be
required to deliver to the trustee an opinion of counsel that the deposit and
related defeasance would not cause the holders of the Debt Securities to
recognize income, gain or loss for federal income tax purposes. If we elect
legal defeasance, that opinion of counsel must be based upon a ruling from the
Internal Revenue Service or a change in law to that effect.

Governing Law

New York law governs the Indenture and the Debt Securities.

Trustee

The Indenture contains limitations on the right of the trustee, if it
becomes one of our creditors, to obtain payment of claims or to realize on
property received for those claims, as security or otherwise. The trustee is
permitted to engage in other transactions with us. If, however, it acquires any
conflicting interest, it must eliminate that conflict or resign.

Form, Exchange, Registration and Transfer

We will issue the Debt Securities in registered form, without interest
coupons. We will not charge a service charge for any registration of transfer
or exchange of the Debt Securities. We may, however, require the payment of any
tax or other governmental charge payable for that registration.

Holders may exchange Debt Securities of any series for other Debt Securities
of the same series, the same total principal amount and the same terms but in
different authorized denominations in accordance with the Indenture. Holders
may present Debt Securities for registration of transfer at the office of the
security registrar or any transfer agent we designate. The security registrar
or transfer agent will effect the transfer or exchange when it is satisfied
with the documents of title and identity of the person making the request.

We have appointed the trustee as security registrar for the Debt Securities.
If a prospectus supplement refers to any transfer agents initially designated
by us, we may at any time rescind that designation or approve a change in the
location through which any transfer agent acts. We are required to maintain an
office or agency for transfers and exchanges in each place of payment. We may
at any time designate additional transfer agents for any series of Debt
Securities.

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In the case of any redemption, neither the security registrar nor the
transfer agent will be required to register the transfer or exchange of any
Debt Security either:

. during a period beginning 15 business days prior to the mailing of the
relevant notice of redemption and ending on the close of business on the
day of mailing of that notice; or

. if we have called the Debt Security for redemption in whole or in part,
except the unredeemed portion of any Debt Security being redeemed in
part.

Payment and Paying Agents

Unless we inform you otherwise in a prospectus supplement, payments on the
Debt Securities will be made in U.S. dollars at the office of the trustee. At
our option, however, we may make payments by check mailed to the holder's
registered address or, for global Debt Securities, by wire transfer. Unless we
inform you otherwise in a prospectus supplement, we will make interest payments
to the person in whose name the Debt Security is registered at the close of
business on the record date for the interest payment.

Unless we inform you otherwise in a prospectus supplement, we will designate
the trustee as our paying agent for payments on Debt Securities issued under
the Indenture. We may at any time designate additional paying agents or rescind
the designation of any paying agent or approve a change in the office through
which any paying agent acts.

Subject to the requirements of any applicable abandoned property laws, the
trustee and paying agent will pay to us upon written request any money they are
holding for payments on the Debt Securities that remain unclaimed for two years
after the date upon which that payment has become due. After payment to us,
holders entitled to the money must look to us for payment. In that case, all
liability of the trustee or paying agent with respect to that money will cease.

Book-Entry Debt Securities

We may issue the Debt Securities of a series in the form of one or more
global Debt Securities that would be deposited with a depositary or its nominee
identified in the prospectus supplement. We may issue global Debt Securities in
either temporary or permanent form. We will describe in the prospectus
supplement the terms of any depositary arrangement and the rights and
limitations of owners of beneficial interests in any global Debt Security.

PLAN OF DISTRIBUTION

We may sell the Debt Securities offered under this prospectus through
underwriters, agents or dealers or directly to purchasers.

Underwriters

The applicable prospectus supplement will identify any agents or
underwriters and describe their compensation, including underwriting discount.
The prospectus supplement will also describe other terms of the offering,
including any discounts or concessions allowed or reallowed or paid to dealers
and any securities exchanges on which the offered Debt Securities may be
listed.

The distribution of Debt Securities under this prospectus may occur from
time to time in one or more transactions at a fixed price or prices, which may
be changed, at market prices prevailing at the time of sale, at prices related
to those prevailing market prices or at negotiated prices.

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Agents and Direct Sales

If the applicable prospectus supplement indicates, we will authorize dealers
or our agents to solicit offers by various institutions to purchase offered
Debt Securities from us pursuant to contracts that provide for payment and
delivery on a future date. We must approve all institutions, but they may
include, among others:

. commercial and savings banks;

. insurance companies;

. pension funds;

. investment companies; and

. educational and charitable institutions.

The institutional purchaser's obligations under a contract will be subject
only to the condition that the purchase of the offered Debt Securities at the
time delivery is allowed by any laws that govern the purchaser. The dealers and
our agents will not be responsible for the validity or performance of the
contracts.

General Information

Underwriters, dealers and agents participating in a sale of Debt Securities
may be deemed to be underwriters as defined in the Securities Act of 1933, and
any discounts and commissions received by them and any profit realized by them
on resale of the Debt Securities may be deemed to be underwriting discounts and
commissions under the Securities Act. We may have agreements with the agents,
underwriters and dealers to indemnify them against various civil liabilities,
including liabilities under the Securities Act, or to contribute to payments
that the agents, underwriters or dealers may be required to make as a result of
those civil liabilities.

Unless we indicate differently in a prospectus supplement, we will not list
the Debt Securities on any securities exchange. If we sell a security offered
under this prospectus to an underwriter for public offering and sale, the
underwriter may make a market for that security but is not obligated to do so.
Therefore, we cannot give any assurances to you concerning the liquidity of any
security offered under this prospectus.

Agents and underwriters and their affiliates may be customers of, engage in
transactions with, or perform services for us or our subsidiary companies in
the ordinary course of business.

LEGAL MATTERS

The validity of the Debt Securities will be passed upon for ONEOK by Gable &
Gotwals, Tulsa, Oklahoma. Any underwriters or agents will be advised about
other issues relating to any offering by Jones, Day, Reavis & Pogue, Chicago,
Illinois. Jones, Day, Reavis & Pogue will rely on Gable & Gotwals as to matters
of Oklahoma law. Jones, Day, Reavis & Pogue from time to time acts as counsel
to ONEOK.

EXPERTS

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$240,000,000

ONEOK, INC.

Floating Rate Notes Due April 24, 2002
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PROSPECTUS SUPPLEMENT

April 19, 2000

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Banc of America Securities LLC

Banc One Capital Markets, Inc.

Chase Securities Inc.

Salomon Smith Barney Inc.
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