<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>