Exhibit 99.1

   Written Statement of the Chairman, President and Chief Executive Officer
                    Pursuant to 18 U.S.C. Section 1350

Solely  for the  purposes  of  complying  with 18 U.S.C.  Section  1350,  I, the
undersigned  Chairman,  President and Chief Executive  Officer of Alliant Energy
Corporation (the  "Company"),  hereby certify,  based on my knowledge,  that the
Annual Report on Form 11-K for the Alliant  Energy  Corporation  401(k)  Savings
Plan (the  "Plan") for the year ended  December  31, 2002 (the  "Report")  fully
complies with the  requirements of Section 13(a) of the Securities  Exchange Act
of 1934 and that  information  contained in the Report fairly  presents,  in all
material  respects,  the  financial  condition  and results of operations of the
Plan.

/s/ Erroll B. Davis, Jr.
- ------------------------
Erroll B. Davis, Jr.
June 30, 2003

A signed  original of this written  statement  required by Section 906 has been
provided to the Company  and will be retained by the Company and  furnished  to
the Securities and Exchange Commission or its staff upon request.




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