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, 2001

                                      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













                              Page 1 of 21 pages
                          Exhibit Index is on page 20



                             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.









                                       2



                          ALLIANT ENERGY CORPORATION

                              401(k) SAVINGS PLAN

      FINANCIAL STATEMENTS FOR THE YEARS ENDED DECEMBER 31, 2001 AND 2000,

       SUPPLEMENTAL SCHEDULES FOR THE YEAR ENDED DECEMBER 31, 2001, AND

                         INDEPENDENT AUDITORS' REPORTS









                                       3



                                          ALLIANT ENERGY CORPORATION

                                            401(k) SAVINGS PLAN


                                             TABLE OF CONTENTS




                                                                                                       Page  No.

                                                                                                      
INDEPENDENT AUDITORS' REPORTS                                                                            5-6

FINANCIAL STATEMENTS

         Statements of Net Assets Available for Plan Benefits
         as of December 31, 2001 and 2000                                                                 7

         Statement of Changes in Net Assets Available for Plan Benefits
         for the Year Ended December 31, 2001                                                             8

NOTES TO FINANCIAL STATEMENTS                                                                            9-15

SUPPLEMENTAL SCHEDULES

         Form 5500, Schedule H, Part IV, line 4i - Schedule of Assets (Held At End of Year)
         as of December 31, 2001                                                                          16

         Form 5500, Schedule H, Part IV, line 4i - Schedule of Assets (Acquired and Disposed of
         Within Year) for the Year Ended December 31, 2001                                                17

         Form 5500, Schedule H, Part IV, line 4j - Schedule of Reportable Transactions
         for the Year Ended December 31, 2001                                                             18

SIGNATURES                                                                                                19

EXHIBIT INDEX                                                                                             20

         Independent Auditors' Consent                                                                    21






                                       4


Independent Auditors' Report

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

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

We conducted our audit 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
audit provides a reasonable basis for our opinion.

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

Our audit was conducted for the purpose of forming an opinion on the basic
2001 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 2001 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
July 3, 2002

                                       5


Arthur Andersen LLP (Andersen) is the former auditor of the Alliant Energy
Corporation 401(k) Savings Plan (the Plan).  As a result of recent events at
Andersen, Andersen declined the Plan's request to reissue their audit report
dated June 1, 2001 for the fiscal years ended December 31, 2000 and 1999 for
inclusion in the Plan's 11-K filing for the fiscal year ended December 31,
2001.  As such, pursuant to the guidance given in the Temporary Final Rule
and Final Rule: Requirements for Arthur Andersen LLP Auditing Clients,
Release Nos. 33-8070; 34-45590; 35-27503; 39-2395; IA-2018; IC-25464; FR-62;
File No. S7-03-02, the Plan is filing this copy of the latest signed and
dated accountant's report issued by Andersen for such periods.


Report of Independent Public Accountants


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, 2000 and 1999, and the related statement of changes in net
assets available for plan benefits for the year ended December 31, 2000.
These financial statements and the supplemental schedules referred to below
are the responsibility of the Plan's administrator.  Our responsibility is to
express an opinion on these financial statements and supplemental schedules
based on our audits.

We conducted our audits in accordance with generally accepted auditing
standards.  Those standards require that we plan and perform the audits 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, the financial statements referred to above present fairly, in
all material respects, the net assets available for plan benefits of the Plan
as of December 31, 2000 and 1999, and the changes in net assets available for
plan benefits for the year ended December 31, 2000, in conformity with
generally accepted accounting principles.

Our audits were performed for the purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental schedules, as listed
in the accompanying table of contents, are presented for 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 supplemental schedules are the
responsibility of the Plan's management.  The supplemental schedules have
been subjected to the auditing procedures applied in the audits of the basic
financial statements and, in our opinion, are fairly stated in all material
respects in relation to the basic financial statements taken as a whole.




/s/ ARTHUR ANDERSEN LLP

Milwaukee, Wisconsin
June 1, 2001


                                       6





                                         ALLIANT ENERGY CORPORATION

                                            401(k) SAVINGS PLAN

                            STATEMENTS OF NET ASSETS AVAILABLE FOR PLAN BENEFITS


                                                                                                   December 31,
                                                                                          2001                   2000
                                                                               ---------------------   --------------------
                                                                                                             
    Investment income receivable                                                         $3,862,243             $2,295,832
    Contributions receivable                                                              1,100,180                      -
    Loan payment receivable                                                                       -                 37,280
                                                                               ---------------------   --------------------
      Total receivables                                                                   4,962,423              2,333,112
                                                                               ---------------------   --------------------

    Investments, other than participant promissory notes (Refer to Note 7)              329,894,234            396,861,094
    Participant promissory notes                                                          7,686,036              9,563,617
                                                                               ---------------------   --------------------
        Total investments                                                               337,580,270            406,424,711
                                                                               ---------------------   --------------------

Net assets available for plan benefits                                                 $342,542,693           $408,757,823
                                                                               =====================   ====================


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



                                       7






                                     ALLIANT ENERGY CORPORATION

                                       401(k) SAVINGS PLAN

                   STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR PLAN BENEFITS

                             For the Year Ended December 31, 2001


                                                                                              
 Net assets available for plan benefits
   - beginning of year                                                                       $408,757,823

 Contributions:
     Cash contributions from employees                                                         24,300,679
     Rollovers from other qualified plans                                                         733,210
     Employer contributions:
         Cash                                                                                     721,556
         Cash for purchase of Alliant Energy Corporation common stock                           7,128,868

 Investment activity:
     Investment income                                                                          9,680,299
     Net depreciation in fair value of investments (Refer to Note 7)                          (51,380,764)

 Distributions:
     Transfers to other plans (Refer to Note 10)                                              (39,756,912)
     Distributions to participants                                                            (17,642,066)
                                                                                      --------------------

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



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



                                       8


                      ALLIANT ENERGY CORPORATION
                         401(k) SAVINGS PLAN

                    NOTES TO FINANCIAL STATEMENTS
               YEARS ENDED DECEMBER 31, 2001 AND 2000

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 benefits 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 employees, members of the bargaining units of the former
Interstate Power Company, must complete the one-year (1,000 hour) waiting
period.  (On January 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 employees are also
eligible under the same rules as "regular" employees.

      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 2001 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                         $10,500


      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.

                                       9


      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.

      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 are 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 Common 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 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 $34,216,008 and $33,831,298 at December 31, 2001 and 2000, respectively.
The approximate fair value of these investments was $34,792,937 and
$36,416,741 at December 31, 2001 and 2000, respectively, based on the
discounted cash flows valuation method.  Under the terms of the GIC's, the
average crediting interest rate was 5.87% and 6.61% on December 31, 2001 and
2000, respectively, and is fixed for all contracts.  The GIC's earned an
average rate of 6.55% in 2001.

      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.  The average
duration ranges between 3 and 6 years.

      Janus Adviser Balanced Fund.  Effective June 1, 2001, the Janus Adviser
Balanced Fund replaced the Dreyfus Founders Balanced Fund.  Participants who
had monies invested in the Dreyfus Founders Balanced Fund had their current
and future contributions transferred to the Janus Adviser Balanced Fund.  The
Janus Adviser Balanced Fund is a growth and income fund.  Its objective is to
seek long-term capital growth, consistent with preservation of capital and
balanced by current income.  It normally invests 40% to 60% of its assets in
securities selected primarily for their growth potential and 40% to 60% of
its assets in securities selected primarily for their income potential.  At
least 25% of the fund's assets are normally invested in fixed income senior
securities, which include debt securities and preferred stocks.

                                       10


      American Express Trust Equity Index Fund III.  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.

      American Century Income & Growth Fund.  American Century Income & Growth
Fund is a large-cap value fund.  Its objective is to seek dividend growth,
current income and capital appreciation by investing in securities of the
1,500 largest companies traded in the United States.  The fund may also
invest in foreign securities.

      AXP Growth Fund.  The AXP Growth Fund is a large-cap growth fund.  Its
objective is to seek capital appreciation by investing in securities of those
companies believed to have above-average potential for long-term growth as a
result of new management, marketing opportunities or technical superiority.
The AXP Growth Fund invests primarily in common stocks of medium-to-large
capitalization growth companies.

      Franklin Small - Mid Cap Growth Fund.  The Franklin Small - Mid Cap
Growth Fund (formerly known as the Franklin Small Cap Growth Fund) is a
diversified portfolio which seeks to provide long-term capital appreciation
by investing principally in common stocks of companies with market
capitalization of less than $1.5 billion.  The Franklin Small - Mid Cap
Growth Fund's investment strategy emphasizes companies with potential to
rapidly grow revenues, earnings, or cash flow.

      Marshall International Stock Fund.  The Marshall International Stock
Fund is an international stock fund.  Its objective is to seek long-term
capital appreciation.  The Marshall International Stock Fund invests
primarily in stocks and bonds of foreign companies and governments outside
the United States.

      Alliant Energy Corporation Common Stock Fund.  This fund is invested
primarily in common stock of the Company.  A portion of the fund (0-2% 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.

      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 6.0%
to 10.5% at December 31, 2001 and 6.75% to 11.00% at December 31, 2000.

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.  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.

(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."

                                       11


(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 United States 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.  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
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.

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
request 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 terminated participants at December
31, 2001 and 2000 were $35,556 and $0, 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 December 31, 2001 or December 31, 2000.


                                       12


Note 7.    Other Investment Information

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



                                                                                          2001               2000
                                                                                    ----------------    --------------
                                                                                                       
   Alliant Energy Corporation Common Stock                                            $75,646,312         $69,420,467
        (participant directed: $40,347,322 and $39,224,785, respectively)
        (non-participant directed: $35,298,990 and $30,195,682, respectively)
   American Express Trust Equity Index Fund III                                        75,560,203          95,196,553
   AXP Growth Fund                                                                     55,043,250          91,870,331
   Janus Adviser Balanced Fund                                                         28,772,607                 N/A
   Franklin Small - Mid Cap Growth Fund                                                22,932,386          32,970,044
   Dreyfus Founders Balanced Fund                                                             N/A          34,378,637



      During 2001, 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:



                                                                                       
   AXP Growth Fund                                                                   ($26,085,432)
   American Express Trust Equity Index Fund III                                       (10,562,528)
   Franklin Small - Mid Cap Growth Fund                                                (6,061,288)
   Marshall International Stock Fund                                                   (3,678,027)
   Alliant Energy Corporation Common Stock                                             (3,404,848)
   Janus Adviser Balanced Fund                                                         (1,220,823)
   Dreyfus Founders Balanced Fund                                                        (599,028)
   American Century Income & Growth Fund                                                 (157,027)
   PIMCO Total Return Fund                                                                (36,814)
   American Express Trust Income Fund I                                                   425,051
                                                                               ----------------------
        Net depreciation in fair value of investments                                ($51,380,764)
                                                                               ======================


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:




      Net Assets:                                              December 31, 2001         December 31, 2000
                                                             ----------------------    ----------------------
                                                                                           
           Alliant Energy Corporation Common Stock                  $35,298,990               $30,195,682
           American Express Trust Money Market Fund I                   651,047                 1,969,226
           Contributions receivable                                     257,043                        --
           Investment income receivable                                   1,409                    11,215
                                                             ----------------------    ----------------------
                                                                    $36,208,489               $32,176,123
                                                             ======================    ======================



                                       13




                                                              For the year ended
      Changes in Net Assets:                                   December 31, 2001
                                                             ----------------------
                                                                      
           Employer contributions                                    $7,128,868

           Results of investment activity:
              Investment income                                       2,366,710
              Net depreciation in fair value of investments          (1,655,459)

           Transfers to participant directed investments                (85,332)
           Transfers to other plans (Refer to Note 10)               (2,536,586)
           Distributions to participants                             (1,185,835)
                                                             ----------------------
                                                                     $4,032,366
                                                             ======================



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 December 31, 2001 and 2000, the Plan held 2,491,644 and
2,177,897 shares of Alliant Energy Corporation common stock, respectively.
These transactions qualify as party-in-interest.

Note 10. Amendments and Changes to the Plan

      During 2001, participant accounts for Alliant Energy Corporation
employees who became employees of the Nuclear Management Company, LLC (NMC)
were transferred from the Plan to a 401(k) plan sponsored by the NMC.  The
total amount transferred out of the Plan during 2001 was $39,756,912.
Alliant Energy Corporation owns interests in two nuclear facilities which the
NMC operates under contract.

Note 11. Reconciliation to Form 5500

      GIC's are recorded in the accompanying financial statements at contract
value; however, they are recorded in the Plan's Form 5500 at fair value.  In
addition, distributions payable to terminated 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 December 31, 2001 and 2000:



                                                                      2001                           2000
                                                            --------------------------     --------------------------
                                                                                                 
           Net assets available for plan benefits                    $342,542,693                  $408,757,823
             per financial statements
           Adjustments:
                Difference between contract value and
                   fair value of GIC's at December 31                          --                     2,585,443
                Benefits requested not yet paid                           (35,556)                           --
                                                            --------------------------    ---------------------------
           Amounts reported per Form 5500                            $342,507,137                  $411,343,266
                                                            ==========================    ===========================



                                       14


      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 December 31, 2001:



                                                             Net Depreciation in Fair           Distributions to
                                                               Value of Investments               Participants
                                                            ---------------------------    ---------------------------
                                                                                                  
           Amounts reported per financial statements                ($51,380,764)                  ($17,642,066)
           Adjustments:
                Difference between contract value and
                   fair value of GIC's                                (2,585,443)                            --
                Benefits requested not yet paid                               --                        (35,556)
                                                            ---------------------------    ---------------------------
           Amounts reported per Form 5500                           ($53,966,207)                  ($17,677,622)
                                                            ===========================    ===========================



Note 12. Subsequent Event

      Effective January 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 in their Alliant Energy Corporation Common Stock ESOP
Fund account or continue to have the dividends reinvested in the Alliant
Energy Corporation Common Stock Fund.


                                       15





                                                    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, 2001

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 Money Market Fund I *, 1,903,248 shares       $1,903,248     $1,903,248

Registered Investment Companies   AXP Growth Fund *, 2,038,639 shares                                  78,650,836     55,043,250
                                  Janus Adviser Balanced Fund, 1,256,446 shares                        29,884,311     28,772,607
                                  Franklin Small - Mid Cap Growth Fund, 735,720 shares                 31,840,608     22,932,386
                                  Marshall International Stock Fund, 1,137,193 shares                  16,712,260     11,815,431
                                  PIMCO Total Return Fund, 1,312,310 shares                            13,828,828     13,726,764
                                  American Century Income & Growth Fund, 95,587 shares                  2,660,879      2,612,384

Common/Collective Trusts          American Express Trust Equity Index Fund III *, 2,549,007 shares     73,709,386     75,560,203
                                  American Express Trust Income Fund I *, 132,299 shares                6,842,286      7,665,641

Corporate Stocks:  Common         Alliant Energy Corporation common stock *, 2,491,644 shares          65,232,766     75,646,312

Investment Contracts
(in Stable Capital Fund)          Monumental Life Insurance Company, 5.78%, 12/31/2050                  5,000,134      5,257,884
                                       Synthetic Guaranteed Investment Contract Wrapper                         -       (100,045)
                                  Bank of America NA, 7.72%, 12/31/2050                                 4,427,809      4,372,904
                                       Synthetic Guaranteed Investment Contract Wrapper                         -       (203,950)
                                  Rabobank International, 6.68%, 12/31/2050                             4,171,516      4,119,790
                                       Synthetic Guaranteed Investment Contract Wrapper                         -       (121,018)
                                  CDC Financial Products Inc., 5.43%, 12/31/2050                        2,895,878      2,859,969
                                       Synthetic Guaranteed Investment Contract Wrapper                         -        (37,734)
                                  JP Morgan Chase & Co., 4.81%, 12/31/2050                              2,739,677      2,705,705
                                       Synthetic Guaranteed Investment Contract Wrapper                         -         28,393
                                  UBS Warburg, 5.66%, 12/31/2050                                        2,641,783      2,609,025
                                       Synthetic Guaranteed Investment Contract Wrapper                         -        (41,427)
                                  State Street Bank and Trust Company, 5.00%, 12/31/2050                2,151,981      2,153,289
                                       Synthetic Guaranteed Investment Contract Wrapper                         -          4,681
                                  AIG Financial Products Corp., 7.22%, 12/31/2050                       2,224,908      2,197,319
                                       Synthetic Guaranteed Investment Contract Wrapper                         -        (81,710)
                                  United of Omaha, 2.08%, 5/20/2002                                     2,004,060      2,004,060
                                  John Hancock Life Insurance Company, 7.69%, 3/31/2005                 2,115,670      2,115,670
                                  New York Life Insurance Company, 7.41%, 8/15/2005                     2,056,032      2,056,032
                                  Hartford, 5.21%, 11/15/2006                                           2,018,452      2,018,452
                                  Protective Life Insurance Company, 6.12%, 6/15/2006                   2,085,083      2,085,083
                                  Sunamerica Life Insurance, 2.64%, 4/3/2002                            1,006,534      1,006,534
                                  United of Omaha, 5.45%, 9/9/2004                                      1,016,873      1,016,873

Participant Promissory Notes      Maximum loan--$50,000
                                  Various interest rates -- 6.0% to 10.5%
                                  Primarily maturing within 5 years                                     7,686,036      7,686,036
                                                                                                    -------------- --------------
                                                                                                     $367,507,834   $341,390,041 (1)
                                                                                                    ============== ==============
     (1) The difference between the total current value on this Schedule H, Part IV, Line 4i and the total investments on the
         Statement of Net Assets Available for Plan Benefits is equal to the total accrued interest on the GICs, which is reported
         on the Statement of Net Assets Available for Plan Benefits as investment income receivable at December 31, 2001.
      *  Represents party known to be a party-in-interest to the Plan.



                                       16



                                                       ALLIANT ENERGY CORPORATION

                                                          401(k) SAVINGS PLAN

                     FORM 5500, SCHEDULE H, PART IV, LINE 4i - SCHEDULE OF ASSETS (ACQUIRED AND DISPOSED OF WITHIN YEAR)

                                                     FOR THE YEAR ENDED DECEMBER 31, 2001
                                                                                                             
                                                   Description of investment
                 Identity                           including maturity date,
       of issue, borrower, lessor,               rate of interest, collateral,                   Cost of           Proceeds of
             or similar party                        par or maturity value                     Acquisitions        Dispositions
-------------------------------------  ---------------------------------------------------  -----------------  -----------------

None.



                                       17





                                                    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, 2001


        Identity                                           Total        Total                         Adjusted
  of Party Involved and                   Total Number    Value of      Number      Net Selling       Cost of           Net
  Description of Assets                   of Purchases  Purchases (1)  of Sales      Price (1)      Assets Sold         Gain
  ---------------------                   ------------  ------------   --------    -------------    -----------         ----
                                                                                                      
----------------------------------------------------------------------------------------------------------------------------------

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      329      $36,358,449       282       $41,752,086      $41,752,086         $ -
Alliant Energy Corporation Common Stock          41       15,544,311        20         5,913,621        4,779,295     1,134,326

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

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



                                       18


                                  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 15th day of July, 2002.


                               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.



                                       19


                                 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                          21




We have not been able to obtain, after reasonable efforts, the written
consent from our former independent public accountant, Arthur Andersen LLP,
to our incorporation by reference in the Registration Statement on Form S-8
(No. 333-46735) pertaining to the Alliant Energy Corporation 401(k) Savings
Plan of their report dated June 28, 2001 with respect to the financial
statements and the supplemental schedules of the Alliant Energy Corporation
401(k) Savings Plan included in this Annual Report on Form 11-K for the year
ended December 31, 2000, as required by Section 7 of the Securities Act of
1933, as amended.  Accordingly, you may be unable to recover amounts sought
in any action against Arthur Andersen LLP, the former independent public
accountant, pursuant to the Securities Act of 1933 and the regulations
thereunder, and therefore any right of recovery may be limited as a result of
the lack of that consent.


                                       20