UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549


                                   FORM 11-K


[X]   ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934

      For the fiscal year ended December 31, 2002

                                      or

[ ]   TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934

      For the transition period from              to
                                     ------------    ------------

      Commission File Number:  1-9894

      A.  Full title of the plan and address of the plan, if different from
          that of the issuer named below:

          ALLIANT ENERGY CORPORATION 401(k) SAVINGS PLAN

      B.  Name of issuer of the securities held pursuant to the plan and the
          address of its principal executive office:

                          ALLIANT ENERGY CORPORATION
                           4902 North Biltmore Lane
                           Madison, Wisconsin 53718




                             REQUIRED INFORMATION

      The following financial statements and schedules of the Alliant Energy
Corporation 401(k) Savings Plan, prepared in accordance with the financial
reporting requirements of the Employee Retirement Income Security Act of
1974, as amended, are filed herewith.

























                              Page 1 of 20 pages
                          Exhibit Index is on page 17


                                       1


                          ALLIANT ENERGY CORPORATION

                              401(k) SAVINGS PLAN

             FINANCIAL STATEMENTS AS OF DECEMBER 31, 2002 AND 2001

                   AND FOR THE YEAR ENDED DECEMBER 31, 2002,

       SUPPLEMENTAL SCHEDULES FOR THE YEAR ENDED DECEMBER 31, 2002, AND

                         INDEPENDENT AUDITORS' REPORT













                                       2


                                      ALLIANT ENERGY CORPORATION

                                         401(k) SAVINGS PLAN


                                          TABLE OF CONTENTS




                                                                                                    Page No.


                                                                                                   
INDEPENDENT AUDITORS' REPORT                                                                           4

FINANCIAL STATEMENTS

         Statements of Net Assets Available for Plan Benefits
         as of December 31, 2002 and 2001                                                              5

         Statement of Changes in Net Assets Available for Plan Benefits
         for the Year Ended December 31, 2002                                                          6

NOTES TO FINANCIAL STATEMENTS                                                                         7-13

SUPPLEMENTAL SCHEDULES

         Form 5500, Schedule H, Part IV, line 4i - Schedule of Assets (Held at End of Year)
         as of December 31, 2002                                                                       14

         Form 5500, Schedule H, Part IV, line 4j - Schedule of Reportable Transactions
         for the Year Ended December 31, 2002                                                          15

SIGNATURES                                                                                             16

EXHIBIT INDEX                                                                                          17

         Independent Auditors' Consent                                                                 18

         Written Statement of the Chairman, President and Chief Executive Officer                      19
         Pursuant to 18 U.S.C. Section 1350

         Written Statement of the Executive Vice President and Chief Financial Officer                 20
         Pursuant to 18 U.S.C. Section 1350



                                       3



Independent Auditors' Report

To the Plan Administrator of the Alliant Energy Corporation 401(k) Savings Plan:

We have audited the accompanying statements of net assets available for plan
benefits of the Alliant Energy Corporation 401(k) Savings Plan (the "Plan")
as of December 31, 2002 and 2001, and the related statement of changes in net
assets available for plan benefits for the year ended December 31, 2002.
These financial statements are the responsibility of the Plan's management.
Our responsibility is to express an opinion on these financial statements
based on our audits.

We conducted our audits in accordance with auditing standards generally
accepted in the United States of America.  Those standards require that we
plan and perform the audit to obtain reasonable assurance about whether the
financial statements are free of material misstatement.  An audit includes
examining, on a test basis, evidence supporting the amounts and disclosures
in the financial statements.  An audit also includes assessing the accounting
principles used and significant estimates made by management, as well as
evaluating the overall financial statement presentation.  We believe that our
audits provide a reasonable basis for our opinion.

In our opinion, such financial statements present fairly, in all material
respects, the net assets available for plan benefits of the Plan as of
December 31, 2002 and 2001, and the changes in net assets available for plan
benefits for the year ended December 31, 2002, in conformity with accounting
principles generally accepted in the United States of America.

Our audits were conducted for the purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental schedules listed in
the Table of Contents are presented for the purpose of additional analysis
and are not a required part of the basic financial statements, but are
supplementary information required by the Department of Labor's Rules and
Regulations for Reporting and Disclosure under the Employee Retirement Income
Security Act of 1974.  These schedules are the responsibility of the Plan's
management.  Such schedules have been subjected to the auditing procedures
applied in our audit of the basic 2002 financial statements and, in our
opinion, are fairly stated in all material respects when considered in
relation to the basic financial statements taken as a whole.


/s/ Deloitte & Touche LLP

Milwaukee, Wisconsin
June 10, 2003



                                       4






                                                ALLIANT ENERGY CORPORATION

                                                   401(k) SAVINGS PLAN

                                   STATEMENTS OF NET ASSETS AVAILABLE FOR PLAN BENEFITS


                                                                                              December 31,
                                                                                       2002                   2001
                                                                               ---------------------   --------------------
                                                                                                             
    Investment income receivable                                                         $5,310,516             $3,862,243
    Contributions receivable                                                                      -              1,100,180
                                                                               ---------------------   --------------------
        Total receivables                                                                 5,310,516              4,962,423
                                                                               ---------------------   --------------------

    Investments, other than participant promissory notes (Refer to Note 7)              281,098,340            329,894,234
    Participant promissory notes                                                          7,663,518              7,686,036
                                                                               ---------------------   --------------------
        Total investments                                                               288,761,858            337,580,270
                                                                               ---------------------   --------------------

Net assets available for plan benefits                                                 $294,072,374           $342,542,693
                                                                               =====================   ====================


The accompanying Notes to Financial Statements are an integral part of these statements.



                                       5






                                   ALLIANT ENERGY CORPORATION

                                      401(k) SAVINGS PLAN

                    STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR PLAN BENEFITS

                             For the Year Ended December 31, 2002



                                                                                           
 Net assets available for plan benefits
   - beginning of year                                                                    $342,542,693

 Contributions:
     Cash contributions from employees                                                      22,266,430
     Rollovers from other qualified plans                                                      954,493
     Employer contributions:
         Cash                                                                                  727,111
         Cash for purchase of Alliant Energy Corporation common stock                        6,894,693
     Transfers from other plans (Refer to Note 10)                                             181,488

 Investment activity:
     Investment income                                                                      10,013,841
     Net depreciation in fair value of investments (Refer to Note 7)                       (78,148,277)

 Distributions:
     Distributions to participants                                                         (11,360,098)
                                                                                   --------------------

 Net assets available for plan benefits
   - end of year                                                                          $294,072,374
                                                                                   ====================


 The accompanying Notes to Financial Statements are an integral part of this statement.



                                       6


                      ALLIANT ENERGY CORPORATION
                         401(k) SAVINGS PLAN

                     NOTES TO FINANCIAL STATEMENTS
                     YEAR ENDED DECEMBER 31, 2002

Note 1.    Description of the Plan

      The Alliant Energy Corporation 401(k) Savings Plan (the Plan) is a
qualified defined contribution plan under Section 401(k) of the Internal
Revenue Code (the Code), as amended, and meets the applicable requirements of
the Employee Retirement Income Security Act of 1974, as amended.  The
following brief description of the Plan is provided for general information
purposes only.  More complete information regarding the Plan is provided in
the summary plan description, which has been made available to all eligible
Plan participants.  The Plan is administered by the Employee Total
Compensation Committee (the Committee) and the Plan sponsor is Alliant Energy
Corporate Services, Inc. (a direct subsidiary of Alliant Energy Corporation),
which reserves the right to terminate, amend or modify the Plan if future
conditions warrant such action.

      Any regular employee of Alliant Energy Corporation and its participating
subsidiaries (the Company) age 18 and over may become a participant in the
Plan.  Regular full-time employees and regular part-time employees
customarily scheduled to work at least half-time may participate on the first
day of any calendar month following 30 consecutive days of service.
Part-time employees customarily scheduled to work less than half-time may
participate after 12 months of service during which he or she has earned at
least 1,000 paid hours.  Certain Interstate Power and Light Company
bargaining unit employees, members of the bargaining units of the former
Interstate Power Company, must complete the one-year (1,000 hour) waiting
period.  (On Jan. 1, 2002, Interstate Power Company merged with and into IES
Utilities Inc. and IES Utilities Inc. changed its name to Interstate Power
and Light Company, resulting in no changes to the Plan.)  Wisconsin Power and
Light Company "special temporary" bargaining unit employees are also eligible
under the same rules as "regular" employees.

      Effective Jan. 1, 2002, the Company adopted an Employee Stock Ownership
Plan (ESOP) within the Plan. Under the new provisions, Plan participants have
the option to elect to receive cash for any dividends paid on Company common
stock within the Plan or continue to have the dividends reinvested.  Also,
the Company is eligible for the dividend deduction provisions of Section
404(k) of the Code for common stock held in the ESOP.

      The Company provides guaranteed matching contributions for each $1
contributed by participants up to a maximum of the first 6% of the
participants' compensation.  Other than the exceptions noted below, employee
contribution limits and employee match information for 2002 are as follows:

               Company match for each $1 contributed
                   up to the maximum                                     $0.50

               Eligible employee annual contribution limit as a
                   percentage of compensation                              19%

               Maximum annual contribution limit                        $11,000

      The matching contributions for Alliant Energy Resources, Inc. (Resources)
and Cedar Rapids and Iowa City Railway Company (CRANDIC) employees are
calculated based on a percentage of base pay, without overtime or incentive
pay, and there is a "basic" Company contribution equal to 4% and 2%,
respectively, of base pay.

      Company matching contributions for Resources and CRANDIC employees are
invested at the participants' discretion.  All other matching contributions
by the Company are invested in the Alliant Energy Corporation Common Stock
Fund.

                                       7


      Resources and CRANDIC employees may be eligible for a discretionary
Company contribution of $0.50 for every $1 contributed up to a maximum of the
first 6% of pay in addition to the "basic" Company contribution.  The
discretionary contribution for both Resources and CRANDIC employees is based
on goals established by Resources and is evaluated during the first quarter
of the following year.  The discretionary Company contributions for 2002 and
2001 were $0 and $388,232, respectively.

      Beginning with the 2001 Plan year, an additional Company contribution is
allocated to the accounts of active Plan participants, except for Resources
and CRANDIC employees, as of the last day of the Plan year, who had
contributed 6% of compensation during the Plan year and did not receive a
Company matching contribution equal to 3% of compensation.  The amount of the
additional Company contribution is the difference between 3% of compensation
during the Plan year and the amount of Company matching contributions
previously received during the Plan year.

      Participants are immediately vested in their employee and employer
contributions.

      Contributions under the Plan are held and invested, until distribution,
in a Trust Fund maintained by American Express Trust Company (the Trustee), a
division of American Express Financial Advisors Inc.

      The investment options available to participants at Dec. 31, 2002 were
Stable Capital Fund, PIMCO Total Return Fund, American Express Trust
Short-Term Horizon (25:75) Fund, American Express Trust Long-Term Horizon
(65:35) Fund, Dodge & Cox Stock Fund, American Express Trust Long-Term
Horizon (80:20) Fund, American Express Trust Equity Index Fund III,
Undiscovered Managers Small Cap Value Fund, Vanguard Mid-Cap Index Fund,
Putnam International Growth Fund, The Growth Fund of America, The Brown
Capital Management Small Company Fund, Alliant Energy Corporation Company
Stock Fund, or a combination of the thirteen funds.  The investment options
available to participants at Dec. 31, 2001 were Stable Capital Fund, PIMCO
Total Return Fund, Janus Adviser Balanced Fund, American Express Trust Equity
Index Fund III, American Century Income & Growth Fund, AXP Growth Fund,
Franklin Small - Mid Cap Growth Fund, Marshall International Stock Fund,
Alliant Energy Corporation Common Stock Fund, or a combination of the nine
funds.  Additionally, participants may subsequently redesignate the
distribution of future contributions or transfer existing balances between
investment funds on a daily basis, subject to the limits set forth in the
Plan.  Company matching contributions invested in the Alliant Energy
Corporation Company Stock Fund may not be transferred to any other investment
fund, except for contributions made for CRANDIC and Resources employees as
previously described; however, Company matching contributions may be
transferred by certain participants during the 30-day period immediately
prior to retirement.  A brief description of the investment options at Dec.
31, 2002 is as follows:

      Stable Capital Fund.  The Stable Capital Fund is a stable value fund.
Its objective is to preserve principal while seeking a competitive level of
current income.  The Stable Capital Fund is intended to be a lower risk
investment with a higher return than is typically offered by money market
funds, while it maintains liquidity and safety of principal.  The fund is
invested primarily in Guaranteed Investment Contracts (GIC's) issued by one
or more insurance companies or other financial institutions.  The fund may
also invest in the American Express Trust Income Fund I and the American
Express Trust Money Market Fund I.  The carrying value of all GIC investments
was $36,564,953 and $34,216,008 at Dec. 31, 2002 and 2001, respectively.  The
approximate fair value of these investments was $43,781,042 and $34,792,937
at Dec. 31, 2002 and 2001, respectively, based on the discounted cash flows
valuation method.  Under the terms of the GIC's, the weighted average
crediting interest rate was 5.62% and 5.87% on Dec. 31, 2002 and 2001,
respectively, and is fixed for all contracts.  The GIC's earned an average
rate of 5.90% in 2002.

      PIMCO Total Return Fund.  The PIMCO Total Return Fund is an actively
managed, intermediate maturity bond portfolio.  Its objective is to maximize
total return, consistent with preservation of capital and prudent investment
management, in order to exceed the returns of the bond market as a whole as
represented by the Lehman Brothers Aggregate Bond Index.  It invests in a
portfolio of intermediate maturity bonds, typically with a majority in
treasury and mortgage-backed bonds.  The average duration ranges between 3
and 6 years.

      American Express Trust Short-Term Horizon (25:75) Fund.  The American
Express Trust Short-Term Horizon (25:75) Fund is a lifestyle fund.  Its
objective is to seek to create a diversified portfolio with a conservative

                                       8


risk profile appropriate for individuals with short-term time horizons.  It
invests in a predetermined mix of growth, growth/income, income and money
market (cash equivalent) investment funds.

      American Express Trust Long-Term Horizon (65:35) Fund.  Effective Sept.
3, 2002, the American Express Trust Long-Term Horizon (65:35) Fund replaced
the Janus Adviser Balanced Fund.  Participants who had monies invested in the
Janus Adviser Balanced Fund had their current and future contributions
transferred to the American Express Trust Long-Term Horizon (65:35) Fund.
The American Express Trust Long-Term Horizon (65:35) Fund is a lifestyle
fund.  Its objective is to seek to create a diversified portfolio with a
conservative risk profile appropriate for individuals with long-term time
horizons.  It invests in a predetermined mix of growth, growth/income and
income investment funds.

      Dodge & Cox Stock Fund.  Effective Sept. 3, 2002, the Dodge & Cox Stock
Fund replaced the American Century Income & Growth Fund.  Participants who
had monies invested in the American Century Income & Growth Fund had their
current and future contributions transferred to the Dodge & Cox Stock Fund.
The Dodge & Cox Stock Fund is a large cap value fund.  Its primary objective
is to seek long-term growth of principal and income and secondary objective
is to achieve a reasonable current income.  It invests primarily in a broadly
diversified and carefully selected portfolio of common stock.  The fund
typically invests at least 80% of its total assets in common stock.

      American Express Trust Long-Term Horizon (80:20) Fund.  The American
Express Trust Long-Term Horizon (80:20) Fund is a lifestyle fund.  Its
objective is to seek to create a diversified portfolio with a moderate risk
profile appropriate for individuals with long-term time horizons.  It invests
in a predetermined mix of growth, growth/income and income investment funds.

      American Express Trust Equity Index Fund III.  The American Express
Trust Equity Index Fund III is a growth and income fund.  Its objective is to
provide investment results that correspond to the price and yield performance
of publicly traded stocks, in aggregate, as represented by the Standard &
Poors' 500 Composite Stock Price Index (S&P 500).  It invests in a portfolio
consisting primarily of common stocks of the S&P 500.

      Undiscovered Managers Small Cap Value Fund.  The Undiscovered Managers
Small Cap Value Fund is a small cap value fund.  Its objective is to seek
long-term growth of capital by primarily investing in common stocks of
companies with smaller market capitalizations.

      Vanguard Mid-Cap Index Fund.  The Vanguard Mid-Cap Index Fund is a mid
cap/core fund.  Its objective is to seek long-term capital growth by tracking
the performance of the Standard & Poor's MidCap 400 Index, which comprises a
market-weighted growth of medium-sized United States of America (U.S.)
companies.  It invests in these medium-sized U.S. companies.

      Putnam International Growth Fund.  Effective Sept. 3, 2002, the Putnam
International Growth Fund replaced the Marshall International Stock Fund.
Participants who had monies invested in the Marshall International Stock Fund
had their current and future contributions transferred to the Putnam
International Growth Fund.  The Putnam International Growth Fund is a foreign
stock fund.  It seeks capital appreciation by investing in common stocks of
companies located outside the U.S.

      The Growth Fund of America.  Effective Sept. 3, 2002, The Growth Fund of
America replaced the AXP Growth Fund.  Participants who had monies invested
in the AXP Growth Fund had their current and future contributions transferred
to The Growth Fund of America.  The Growth Fund of America is a large cap
growth fund.  It seeks to achieve long-term growth of capital.  It invests
primarily in common stocks of companies that appear to offer superior
opportunities for growth of capital.

      The Brown Capital Management Small Company Fund.  Effective Sept. 3,
2002, The Brown Capital Management Small Company Fund replaced the Franklin
Small-Mid Cap Growth Fund.  Participants who had monies invested in the
Franklin Small-Mid Cap Growth Fund had their current and future contributions
transferred to The Brown Capital Management Small Company Fund.  The Brown
Capital Management Small Company Fund is a small cap growth fund.  It seeks

                                       9


capital appreciation by investing primarily in equities issued by companies
with total operating revenues of $250 million or less.

      Alliant Energy Corporation Company Stock Fund.  This fund is invested
primarily in common stock of the Company.  A portion of the fund (1-2% of
total fund assets) may also be invested in the American Express Trust Money
Market Fund I to help provide liquidity for transfers out of the fund.
Purchases and sales of common stock are made by the Trustee on the open
market.  Under the ESOP, Plan participants have the option to elect to
receive cash for any dividends paid on Company common stock within this fund
or continue to have the dividends reinvested.

      Participant Loans.  The Plan has provisions under which participants may
take loans up to the lesser of $50,000 or 50% of their total account balance
(a $1,000 minimum loan amount and a maximum of three loans for each
participant also apply).  The Committee determines the loan interest rate
pursuant to the Plan.  Interest rates on participant loans ranged from 5.25%
to 10.5% at Dec. 31, 2002 and 6.0% to 10.5% at Dec. 31, 2001.

Note 2.    Summary of Significant Accounting Policies

(a) Basis of Accounting - The financial statements have been prepared on the
accrual basis of accounting.

(b) Valuation of Investments and Income Recognition - All GIC's held by the
Plan are fully benefit responsive and are valued at contract value, which
represents contributions made under the contract, plus interest at the
contract rate (less funds used to pay plan benefits).  Participant loans are
carried at unpaid principal balances due, which approximates fair value.  All
other Plan investments are carried at fair value as determined by quoted
market prices.  Interest income is accrued when earned.  Dividend income is
recorded on the ex-dividend date.  Investment transactions are recorded on
the trade date.

(c) Net Depreciation in Fair Value of Investments - Net realized and
unrealized depreciation is recorded in the accompanying statement of changes
in net assets available for plan benefits as "Net depreciation in fair value
of investments."

(d) Payment of Benefits - Benefit payments to participants are recorded when
paid.

(e) Expenses - Investment management fees are paid from investment earnings
prior to crediting earnings to the individual participant account balances.
Most other Plan administrative expenses are absorbed by the Company.

(f) Use of Estimates - The preparation of financial statements in conformity
with accounting principles generally accepted in the U.S. requires the Plan
administrator to make estimates and assumptions that affect the reported
amounts of net assets available for plan benefits at the date of the
financial statements and the reported amounts of changes in net assets
available for plan benefits during the reporting period.  Actual results
could differ from those estimates.

(g) Risk and Uncertainties - The Plan invests in various investments,
including pooled investment funds, mutual funds, common stock of the Company
and investment contracts.  Investments, in general, are exposed to various
risks, such as interest rate, credit, and overall market volatility.  Due to
the level of risk associated with certain investments, it is reasonably
possible that changes in the values of certain investments will occur in the
near term and that such changes could materially affect the amounts reported
in the financial statements.

Note 3.    Tax Status

      The Internal Revenue Service has determined and informed the Company by
a letter dated July 31, 1996, that the Plan and related trust are designed in
accordance with the applicable sections of the Code.  The Plan has been
amended since receiving the determination letter and the Company has filed
for a new determination letter, however, the Plan administrator and the
Plan's tax counsel believe that the Plan is designed and is currently being

                                       10


operated in compliance with the applicable requirements of the Code.  It is
the intention of the Company to adopt any amendments necessary to maintain
the qualified status of the Plan.

Note 4.    Plan Termination Provisions

      Upon termination of the Plan in its entirety, each participant is
entitled to receive, in accordance with the terms of the Plan, the entire
balance in the participant account.  The Company has no intention to
terminate the Plan.

Note 5.    Withdrawals and Distributions

      Withdrawals from participants' account balances will be made to
participants while they are employed due to an election made by certain
participants, reaching age 59-1/2 for certain participants or 70-1/2, or
requests due to special "hardship" circumstances.  Distributions from the
Plan will be made upon termination of employment (by retirement, death,
disability or otherwise) if the participant's account balance is less than
$5,000.  If the participant's account balance exceeds $5,000, the participant
may elect to defer payment until he or she is age 70-1/2.  Distributions can
be either in the form of a lump sum or substantially equal annual
installments.  The unpaid portion of all loans made to the participant,
including accrued interest, will be deducted from the amount of the
participant account to be distributed.  Distributions payable to participants
at Dec. 31, 2002 and 2001 were $222,154 and $35,556, respectively.
Distributions payable are not recorded in the accompanying financial
statements, however, they are recorded in the Plan's Form 5500 (refer to Note
11).

Note 6.    Derivative Financial Instruments

      The Plan did not invest in any material derivative financial instruments
during the years ended Dec. 31, 2002 and 2001.

Note 7.    Other Investment Information

      Investments held which were greater than 5% of the Plan's net assets
available for plan benefits as of Dec. 31 were as follows:



                                                                                         2002               2001
                                                                                   ----------------    --------------
                                                                                                       
   American Express Trust Equity Index Fund III                                       $56,853,595         $75,560,203
   Alliant Energy Corporation Common Stock                                             52,468,184          75,646,312
        (participant directed: $26,255,132 and $40,347,322, respectively)
        (non-participant directed: $26,213,052 and $35,298,990, respectively)
   The Growth Fund of America                                                          42,640,545                 N/A
   American Express Trust Long-Term Horizon (65:35) Fund                               27,051,550                 N/A
   PIMCO Total Return Fund                                                             21,384,606                 N/A
   The Brown Capital Management Small Company Fund                                     16,565,951                 N/A
   AXP Growth Fund                                                                            N/A          55,043,250
   Janus Adviser Balanced Fund                                                                N/A          28,772,607
   Franklin Small-Mid Cap Growth Fund                                                         N/A          22,932,386



                                       11


      During 2002, the Plan's investments, including gains and losses on
investments acquired and disposed of, as well as held during the year,
appreciated (depreciated) in value as follows:



                                                                                       
   Alliant Energy Corporation Common Stock                                           ($37,615,805)
   American Express Trust Equity Index Fund III                                       (17,070,355)
   AXP Growth Fund                                                                    (11,575,796)
   Franklin Small-Mid Cap Growth Fund                                                  (7,459,251)
   Janus Adviser Balanced Fund                                                         (1,800,391)
   Marshall International Stock Fund                                                   (1,272,159)
   American Century Income & Growth Fund                                                 (611,920)
   Putnam International Growth Fund                                                      (418,556)
   The Brown Capital Management Small Company Fund                                       (357,955)
   American Express Trust Long-Term Horizon (65:35) Fund                                 (269,277)
   The Growth Fund of America                                                            (262,246)
   Dodge & Cox Stock Fund                                                                 (70,540)
   Vanguard Mid-Cap Index Fund                                                             (7,153)
   Undiscovered Managers Small Cap Value Fund                                               1,292
   American Express Trust Long-Term Horizon (80:20) Fund                                    1,642
   American Express Trust Short-Term Horizon (25:75) Fund                                   6,393
   PIMCO Total Return Fund                                                                224,468
   American Express Trust Income Fund I                                                   409,332
                                                                               ----------------------
        Net depreciation in fair value of investments                                ($78,148,277)
                                                                               ======================


Note 8.    Non-Participant Directed Investments

      Information about the net assets and the significant components of the
changes in net assets relating to the non-participant directed investments
was as follows:



                                                                               As of Dec. 31,
      Net Assets:                                                      2002                      2001
                                                             ----------------------    ----------------------
                                                                                            
           Alliant Energy Corporation Common Stock                  $26,213,052               $35,298,990
           American Express Trust Money Market Fund I                   464,894                   651,047
           Investment income receivable                                     558                     1,409
           Contributions receivable                                          --                   257,043
                                                             ----------------------    ----------------------
                                                                    $26,678,504               $36,208,489
                                                             ======================    ======================




                                                               For the Year Ended
      Changes in Net Assets:                                     Dec. 31, 2002
                                                             -----------------------
                                                                     
           Employer contributions                                    $6,894,693

           Results of investment activity:
              Investment income                                       2,690,183
              Net depreciation in fair value of investments         (18,343,206)

           Transfers to participant directed investments                (87,897)
           Distributions to participants                               (683,758)
                                                             -----------------------
                                                                    ($9,529,985)
                                                             =======================


Note 9.    Related Party Transactions

      Certain Plan investments are shares of mutual funds and trust funds
managed by an affiliate of the Trustee and shares of common stock of the
Company.  As of Dec. 31, 2002 and 2001, the Plan held 3,170,283 and 2,491,644
shares of Alliant Energy Corporation common stock, respectively.  These
transactions qualify as party-in-interest.

                                       12


Note 10. Amendments and Changes to the Plan

      In July 2002, the Plan was amended to allow SVBK Consulting Group, Inc.
(a subsidiary of Resources) employees who were actively employed on Aug. 17,
2001 participation in the Plan and account balances in the SVBK Consulting
Group, Inc. 401(k) Profit Sharing Plan to be transferred into the Plan as a
plan to plan transfer.  The total amount transferred into the Plan during
2002 was $181,488.

Note 11. Reconciliation to Form 5500

      Distributions payable to participants are not included in the
accompanying financial statements, however, they are recorded in the Plan's
Form 5500.  The following table reconciles net assets available for plan
benefits per the financial statements to the Form 5500 as filed by the
Company for the year ended Dec. 31, 2002 and 2001:



                                                                      2002                           2001
                                                            --------------------------     --------------------------
                                                                                                  
           Net assets available for plan benefits
             per financial statements                                $294,072,374                  $342,542,693
           Adjustments:
                Benefits requested not yet paid                          (222,154)                      (35,556)
                                                            --------------------------    ---------------------------
           Amounts reported per Form 5500                            $293,850,220                  $342,507,137
                                                            ==========================    ===========================


      The following table reconciles changes in net assets available for plan
benefits per the financial statements to the Form 5500 as filed by the
Company for the year ended Dec. 31, 2002:



                                                                 Distributions to
                                                                   Participants
                                                            ---------------------------
                                                                      
           Amounts reported per financial statements                ($11,360,098)
           Adjustments:
                Changes in benefits requested not yet paid              (186,598)
                                                            ---------------------------
           Amounts reported per Form 5500                           ($11,546,696)
                                                            ===========================



Note 12. Subsequent Events

      Effective March 14, 2003, three new investment options were added to the
Plan, which were the Dreyfus Premier Emerging Market Fund, American Express
Trust Bond Index Fund II and Self-Managed Brokerage Account (SMBA).  The SMBA
allows participants to invest in a wide range of mutual funds.

      Effective April 1, 2003, eligible employees can elect to make deferred
cash contributions up to a maximum of 50% of compensation.

      For 2003, participants who will be at least 50 years old by Dec. 31,
2003, are eligible to make catch-up contributions of up to $2,000.  These
catch-up contributions are not eligible for any Company match.


                                       13



                                                       ALLIANT ENERGY CORPORATION

                                                           401(k) SAVINGS PLAN

                           FORM 5500, SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR)

                                                         AS OF DECEMBER 31, 2002

Identity of issue, borrower,               Description of investment including maturity date,                          Current
lessor, or similar party                  rate of interest, collateral, par or maturity value             Cost          Value
--------------------------------- ------------------------------------------------------------------ -------------- -------------
                                                                                                                
Interest Bearing Cash             American Express Trust U.S. Government Securities I *,
                                       1,752,677 shares                                                 $1,752,677    $1,752,677
                                  American Express Trust Money Market Fund I *, 1,526,586 shares         1,526,586     1,526,586

Registered Investment Companies   Undiscovered Managers Small Cap Value Fund, 27,132 shares                440,632       443,877
                                  The Growth Fund of America, 2,308,638 shares                          42,875,148    42,640,545
                                  Putnam International Growth Fund, 629,827 shares                      10,668,520    10,335,460
                                  PIMCO Total Return Fund, 2,004,180 shares                             21,363,704    21,384,606
                                  Dodge & Cox Stock Fund, 69,499 shares                                  6,155,766     6,119,370
                                  The Brown Capital Management Small Company Fund, 789,607 shares       16,846,051    16,565,951
                                  Vanguard Mid-Cap Index Fund, 58,102 shares                               581,407       574,049
                                  American Express Trust Short-Term Horizon (25:75) Fund*,
                                       21,110 shares                                                       365,140       371,722
                                  American Express Trust Long-Term Horizon (65:35) Fund*,
                                       2,790,258 shares                                                 27,268,715    27,051,550
                                  American Express Trust Long-Term Horizon (80:20) Fund*,
                                       6,656 shares                                                        122,752       124,821

Common/Collective Trusts          American Express Trust Equity Index Fund III *, 2,462,794 shares      71,263,790    56,853,595
                                  American Express Trust Income Fund I *, 132,299 shares                 6,842,286     8,074,973
                                  American Express Trust Investment Grade Bond Fund*, 341,030 shares     4,989,956     5,161,495

Corporate Stocks:  Common         Alliant Energy Corporation common stock *, 3,170,283 shares           79,721,630    52,468,184

Corporate Stocks:  Preferred      Conseco Inc., 1 share                                                          1            18

Corporate Bonds                   Americredit 2002-B A3, 3.78%, 02/12/07                                   199,984       204,992
                                  Amcar 2002-C AR, 3.55%, 02/12/08                                          99,982       101,638
                                  Banc of America, 3.37%, 7/11/43                                          484,533       493,138
                                  FSPC T-17 A4 ABS HEL, 6.93%, 01/25/26                                  1,999,924     2,092,884
                                  FHLMC Benchmark, 3.25%, 11/15/04                                       1,015,136     1,028,016
                                  LB-UBS 2002-A2, 4.90%, 06/16/26                                          200,995       211,195
                                  LB-UBS 2002-C4 A2, 4.02%, 09/15/26                                       100,499       101,635
                                  Morgan Stanley 2002-IQ2 A1, 4.09%, 12/15/35                              186,401       192,928

Government Obligations            FHLMC Gold #E90136, 6.00%, 6/1/17                                        449,256       453,035
                                  FHLMC #E90286, 6.00%, 6/1/17                                             986,198       994,942
                                  FHLMC Gold #E90472, 6.00%, 7/1/17                                        445,089       448,225
                                  FHLMC Gold #E90555, 6.00%, 7/1/17                                        482,168       485,566
                                  FHLMC #E73231, 5.50%, 12/1/13                                          1,047,784     1,112,592
                                  FHLMC MTN, 3.525%, 12/20/07                                              370,000       376,913
                                  FHLMC Gold #C66932, 6.00%, 5/1/32                                        191,874       198,247
                                  FHLMC Gold #E00553, 6.00%,  6/1/13                                     1,804,256     1,902,230
                                  FHLMC 2393 A CMO, 5.50%, 12/1/12                                         229,374       230,889
                                  FHLMC Benchmark, 3.00%, 7/15/04                                        1,010,952     1,021,769
                                  FNMA 15Yr #252260, 6.00%, 3/1/10                                       1,493,647     1,577,090
                                  FNMA #254187, 5.00%, 12/1/08                                           1,667,463     1,729,125
                                  FNMA #323290, 6.00%, 9/1/13                                              860,103       907,726
                                  FNMA #440734, 6.00%, 12/1/28                                             962,718     1,012,593
                                  FNMA #491003, 6.00%, 5/1/14                                              837,568       844,989
                                  FNMA #545864, 5.50%, 8/1/17                                              387,803       397,221
                                  FNMA 2002-W3 A3, 6.00%, 7/25/24                                        3,008,086     3,186,660
                                  FNMA 2002-W5 A6, 6.00%, 8/25/32                                          251,758       261,533
                                  FNMA 2002-W4 A3, 5.30%, 09/25/24                                         401,000       415,900
                                  FNMA 2002-W9 A3, 5.00%, 12/25/24                                         201,141       205,510
                                  FHLMC 2492-B, 5.50%, 5/15/13                                             407,972       401,822
                                  US Treasury Note, 1.75%, 12/31/04                                      2,106,563     2,106,235

Investment Contracts              Monumental Life Insurance Company, 4.43%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -       (52,560)
                                  Bank of America NA, 8.11%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -      (311,276)
                                  Rabobank International, 8.01%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -      (248,805)
                                  CDC Financial Products Inc., 7.16%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -      (142,629)
                                  JP Morgan Chase & Co., 5.39%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -       (87,189)
                                  UBS Warburg, 7.50%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -      (151,263)
                                  State Street Bank and Trust Company, 4.15%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -       (74,250)
                                  AIG Financial Products Corp., 7.64%, 12/31/2050
                                       Synthetic Guaranteed Investment Contract Wrapper                          -      (150,548)
                                  United of Omaha, 1.58%, 5/20/2005                                      2,002,553     2,002,553
                                  John Hancock Life Insurance Company, 7.69%, 3/31/2005                  2,116,530     2,116,530
                                  New York Life Insurance Company, 7.41%, 8/15/2005                      2,056,032     2,056,032
                                  Hartford, 5.21%, 11/15/2006                                            2,012,842     2,012,842
                                  Protective Life Insurance Company, 6.12%, 6/15/2006                    2,065,495     2,065,495
                                  United of Omaha, 5.45%, 9/9/2004                                       1,016,873     1,016,873

Participant Promissory Notes      Maximum loan -- $50,000
                                  Various interest rates -- 5.25% to 10.5%
                                  Primarily maturing within 5 years                                      7,663,518     7,663,518
                                                                                                     -------------- -------------
                                                                                                      $335,608,831  $293,862,040 (1)
                                                                                                     ============== ===============
     (1) The difference between the total current value on this Schedule H, Part IV, Line 4i and the total investments
         on the Statements of Net Assets Available for Plan Benefits is equal to accrued interest on the GICs.

      *   Represents party known to be a party-in-interest to the Plan.


                                       14



                                                ALLIANT ENERGY CORPORATION

                                                   401(k) SAVINGS PLAN

                     FORM 5500, SCHEDULE H, PART IV, LINE 4j - SCHEDULE OF REPORTABLE TRANSACTIONS

                                           FOR THE YEAR ENDED DECEMBER 31, 2002


            Identity
      of Party Involved and                 Total Number    Total Value    Total Number  Net Selling    Adjusted Cost        Net
      Description of Assets                 of Purchases  of Purchases (1)   of Sales     Price (1)     of Assets Sold   Gain (Loss)
      ---------------------                 ------------  ----------------   --------     ---------     --------------   -----------
------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            
Single Transaction Exceeds 5% of Value:

None.

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

Series of Transactions With Same Broker
  Exceeds 5% of Value:

None.

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

Series of Transactions In Same Security
  Exceeds 5% of Value:

American Express Trust Money Market Fund I         303       $38,615,468         311       $38,992,130      $38,992,130       $ -

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

Single Transaction With One Broker Exceeds
  5% of Value:

None.

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

  (1) The purchase/selling price was equal to the fair value on the date of purchase/sale.



                                       15


                                  SIGNATURES

      Pursuant to the requirements of the Securities Exchange Act of 1934, the
Employee Total Compensation Committee, which administers the Plan, has duly
caused this Annual Report to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Madison, and State of Wisconsin, on
this 30th day of June, 2003.


                               ALLIANT ENERGY CORPORATION
                               401(k) SAVINGS PLAN


                               /s/  Pamela J. Wegner
                               --------------------------------------
                                        Pamela J. Wegner


                               The foregoing person is the Executive Vice
                               President-Shared Solutions of Alliant Energy
                               Corporation and the President of Alliant Energy
                               Corporate Services, Inc.



                                       16


                                                EXHIBIT INDEX


                                         ALLIANT ENERGY CORPORATION
                                            401(k) SAVINGS PLAN

                                                FORM 11-K





                                                                                                 Page Number in
                                                                                             Sequentially Numbered
  Exhibit No.                                      Exhibit                                          Form 11-K
  -----------                                      -------                                          ---------
                                                                                                 
     23                               Independent Auditors' Consent                                    18

     99.1                             Written Statement of the Chairman, President                     19
                                           and Chief Executive Officer
                                           Pursuant to 18 U.S.C. Section 1350

     99.2                             Written Statement of the Executive Vice                          20
                                           President and Chief Financial Officer
                                           Pursuant to 18 U.S.C. Section 1350




                                       17