<ARTICLE>                                           UT
<LEGEND>
THIS SCHEDULE  CONTAINS SUMMARY FINANCIAL  INFORMATION  EXTRACTED FROM THE MARCH
31, 1999 FINANCIAL  STATEMENTS INCLUDED IN INTERSTATE ENERGY  CORPORATION'S FORM
10-Q AND IS QUALIFIED IN ITS ENTIRETY BY REFRENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<CIK>                         0000352541
<NAME>                        INTERSTATE ENERGY CORPORATION
<MULTIPLIER>                                   1,000
       
                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                              DEC-31-1999
<PERIOD-START>                                 JAN-01-1999
<PERIOD-END>                                   MAR-31-1999
<BOOK-VALUE>                                   PER-BOOK
<TOTAL-NET-UTILITY-PLANT>                      3,069,213
<OTHER-PROPERTY-AND-INVEST>                    1,202,097
<TOTAL-CURRENT-ASSETS>                         362,599
<TOTAL-DEFERRED-CHARGES>                       159,066
<OTHER-ASSETS>                                 278,147
<TOTAL-ASSETS>                                 5,071,122
<COMMON>                                       779
<CAPITAL-SURPLUS-PAID-IN>                      913,728
<RETAINED-EARNINGS>                            777,716 <F1>
<TOTAL-COMMON-STOCKHOLDERS-EQ>                 1,692,223
<PREFERRED-MANDATORY>                          24,431
<PREFERRED>                                    89,102
<LONG-TERM-DEBT-NET>                           1,545,251
<SHORT-TERM-NOTES>                             50,027
<LONG-TERM-NOTES-PAYABLE>                      56,975
<COMMERCIAL-PAPER-OBLIGATIONS>                 64,000
<LONG-TERM-DEBT-CURRENT-PORT>                  54,084
<PREFERRED-STOCK-CURRENT>                      0
<CAPITAL-LEASE-OBLIGATIONS>                    11,499
<LEASES-CURRENT>                               12,146
<OTHER-ITEMS-CAPITAL-AND-LIAB>                 1,471,384
<TOT-CAPITALIZATION-AND-LIAB>                  5,071,122
<GROSS-OPERATING-REVENUE>                      546,855
<INCOME-TAX-EXPENSE>                           24,872  <F2>
<OTHER-OPERATING-EXPENSES>                     453,868
<TOTAL-OPERATING-EXPENSES>                     453,868
<OPERATING-INCOME-LOSS>                        92,987
<OTHER-INCOME-NET>                             8,705
<INCOME-BEFORE-INTEREST-EXPEN>                 101,692
<TOTAL-INTEREST-EXPENSE>                       33,400
<NET-INCOME>                                   43,420
<PREFERRED-STOCK-DIVIDENDS>                    1,676
<EARNINGS-AVAILABLE-FOR-COMM>                  41,744
<COMMON-STOCK-DIVIDENDS>                       38,834
<TOTAL-INTEREST-ON-BONDS>                      90,353
<CASH-FLOW-OPERATIONS>                         170,152
<EPS-PRIMARY>                                  0.54
<EPS-DILUTED>                                  0.54
        
<FN>
<F1>  Includes $237,434 of Accumulated Other Comprehensive Income.
<F2>  Income tax expense is not included in Operating Expense in the 
      Consolidated Statements of Income.
</FN>