
<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED CONDENSED FINANCIAL STATEMENTS OF ONEOK, INC. FOR THE QUARTER ENDED
MARCH 31, 2000, AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL
STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

<S>                             <C>
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-2000
<PERIOD-START>                             JAN-01-2000
<PERIOD-END>                               MAR-31-2000
<CASH>                                          50,001
<SECURITIES>                                         0
<RECEIVABLES>                                  394,444
<ALLOWANCES>                                         0
<INVENTORY>                                     61,345
<CURRENT-ASSETS>                               612,423
<PP&E>                                       3,465,399
<DEPRECIATION>                               1,041,582
<TOTAL-ASSETS>                               3,574,548
<CURRENT-LIABILITIES>                          721,678
<BONDS>                                      1,122,184
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                        199
<COMMON>                                           316
<OTHER-SE>                                   1,185,993
<TOTAL-LIABILITY-AND-EQUITY>                 3,574,548
<SALES>                                        823,949
<TOTAL-REVENUES>                               823,949
<CGS>                                          558,296
<TOTAL-COSTS>                                  558,296
<OTHER-EXPENSES>                               158,596
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              21,985
<INCOME-PRETAX>                                 99,353
<INCOME-TAX>                                    38,446
<INCOME-CONTINUING>                             60,907
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                        2,115
<NET-INCOME>                                    63,022
<EPS-BASIC>                                       1.84
<EPS-DILUTED>                                     1.28


</TABLE>
