Exhibit 99.1


[GRAPHIC OMITTED][GRAPHIC OMITTED]
One Ameren Plaza
1901 Chouteau Avenue
St. Louis, MO 63103

Contact:

   Media                            Analysts                   Investors
   Tim Fox                          Bruce Steinke              Investor Services
   (314) 554-3120                   (314) 554-2574             invest@ameren.com
   tfox2@ameren.com                 bsteinke@ameren.com

FOR IMMEDIATE RELEASE
- ---------------------

                   AMEREN REPORTS THIRD QUARTER 2003 EARNINGS

     St.  Louis,  Mo.,  Oct. 24,  2003---Ameren  Corporation  (NYSE:  AEE) today
announced  2003 third  quarter net income of $275  million,  or $1.70 per share,
compared to net income of $240 million,  or $1.64 per share ($1.63 diluted),  in
the third  quarter of 2002.  Net income in the third quarter of 2003 included an
after-tax gain of $31 million, or 19 cents per share,  related to the settlement
of a  dispute  over  certain  mine  reclamation  issues  with a  coal  supplier.
Excluding  this item,  third quarter net income was $244  million,  or $1.51 per
share.

     Net income for the first nine months of 2003 was $486 million, or $3.02 per
share,  compared to $414  million,  or $2.88 per share ($2.87  diluted),  in the
first  nine  months of 2002.  The  company  recorded  an  after-tax  gain of $18
million,  or 11 cents  per  share,  in the  first  quarter  of 2003,  due to the
adoption  of a new  accounting  standard  related  to the  recognition  of asset
retirement  obligations.  Excluding  the  gains  on  the  adoption  of  the  new
accounting standard and the coal mine reclamation settlement, net income for the
first nine months of 2003 was $437 million, or $2.72 per share.

     "Once  again,  we  delivered  solid  earnings in the third  quarter of 2003
despite milder summer weather conditions," said Charles W. Mueller, chairman and
chief executive officer of Ameren Corporation.  "Our focus on asset optimization
and cost control continues to reap benefits for all of our stakeholders."

     Gary L. Rainwater,  president and chief operating officer of Ameren, added,
"During the quarter,  weather conditions were considerably  cooler than in 2002,
which reduced our earnings by 25 to 30 cents per share compared to last year. In
addition,  the second phase of electric rate reductions in our Missouri  service
territory reduced third quarter 2003 earnings by 5 cents per

                                    - more -



Add One

share compared to the prior year. However, the good performance of the company's
generating  plants,   higher  power  prices,  lower  expenses  incurred  in  our
pre-CILCORP  acquisition  operations and organic growth significantly offset the
impact of weather and rate reductions."

     Electric  revenues in the third quarter of 2003 increased $131 million,  as
compared  to 2002.  The  acquisition  of CILCORP  Inc.  (including  its  utility
subsidiary  that is now  operating as  AmerenCILCO),  which  increased  electric
revenues by $168 million, and higher interchange power revenues, which increased
by $15 million,  were the key factors behind the quarter's  increased  revenues.
These  increases  were  partially  offset by lower  revenues  from  native  load
customers due to cooler  summer  weather in 2003 compared to 2002, as well as an
incremental  annual electric rate decrease in our Missouri service  territory of
$30 million that went into effect in April 2003.  In the  company's  pre-CILCORP
acquisition service area, weather-sensitive  residential and commercial electric
kilowatthour  sales declined 7 percent in the third quarter of 2003, as compared
to the third quarter of 2002. However,  industrial  electric  kilowatthour sales
increased 1 percent in the company's pre-acquisition service territory.

     Earnings from interchange  power sales by  AmerenEnergy,  Inc. on behalf of
AmerenUE  and  AmerenEnergy  Generating  Company  were 10 cents per share in the
third quarter of 2003, up  approximately  4 cents per share over the same period
in 2002.  This  increase in earnings  was due to higher  power  prices,  greater
availability of the company's low-cost generating plants and reduced demand from
weather-sensitive native load customers.

     Other  operations  and  maintenance  expenses  increased $24 million in the
third quarter of 2003, compared to 2002.  Increased expenses due to the addition
of CILCORP and rising  employee  benefit  costs were  partially  offset by lower
labor costs  resulting  from the voluntary  retirement  program  implemented  at
Ameren in early 2003 and lower generating plant maintenance costs.

     Third  quarter  2003  earnings  per share  were also  unfavorably  impacted
compared to 2002 by higher depreciation expenses and financing costs, as well as
a greater number of common shares outstanding.

     Commenting  on the  CILCORP  acquisition,  Rainwater  added,  "Our  company
remains very focused on the timely  integration of AmerenCILCO,  which continues
to proceed on plan.  In  August,  we  completed  the  integration  of Ameren and
AmerenCILCO  financial  systems,  and we expect the  integration  of operational
systems to be completed by year-end."

                                    - more -


Add Two

     During the third quarter of 2003, the CILCORP  acquisition was accretive to
earnings  by  approximately  2 cents per share,  consistent  with the  company's
expectations.  The company believes the CILCORP acquisition will be accretive to
earnings  in  its  first  full  year  of  operations,  assuming  normal  weather
conditions.

     Ameren  also  announced  today  that it was  narrowing  its  2003  earnings
guidance  range to between  $2.90 and $3.00 per share,  within its original 2003
range of $2.80 to $3.05 per share. This estimate  excludes the gains,  discussed
above,  of 11 cents per share  related  to the  adoption  of the new  accounting
standard and 19 cents per share for the coal mine  reclamation  settlement.  The
company's guidance is subject to, among other things,  plant operations,  timely
integration  of  AmerenCILCO,  weather  conditions,  energy  market and economic
conditions  and  other  risks  and  uncertainties   outlined  in  the  company's
Forward-Looking Statements.

     Ameren will conduct a conference  call for financial  analysts at 9:00 a.m.
(Central  Time) on Friday,  Oct. 24, to discuss  third  quarter  2003  earnings.
Investors, the news media and the public may listen to a live Internet broadcast
of the Ameren  analyst  call at  www.ameren.com  by clicking  on "Third  Quarter
Earnings  Conference  Call," then the  appropriate  audio link. The analyst call
will also be  available  for  replay  on the  Internet  for one year.  Telephone
playback of the conference  call will also be available  beginning at 12:00 p.m.
(Central  Time),  Oct.  24,  until Oct.  31 by  dialing,  U.S.  (800)  428-6051;
international (973) 709-2089, and entering the number: 308455.

     Ameren will also conduct a live  Internet  broadcast at 8:45 a.m.  (Central
Time) on Tuesday,  Oct. 28 of a management  presentation  at the Edison Electric
Institute Financial Conference. The webcast can be accessed at www.ameren.com by
clicking on "Ameren  Corporation  at 38th EEI  Financial  Conference,"  then the
appropriate audio link.

     With  assets  of $13.5  billion,  Ameren  owns a  diverse  mix of  electric
generating plants strategically located in its Midwest market with a capacity of
more than 14,500  megawatts.  Ameren serves 1.7 million  electric  customers and
500,000  natural gas  customers  in a 49,000  square-mile  area of Missouri  and
Illinois.

Forward-Looking Statements
- --------------------------

     Statements made in this release,  which are not based on historical  facts,
are  "forward-looking"  and,  accordingly,  involve risks and uncertainties that
could cause actual results to differ  materially from those discussed.  Although
such "forward-looking"  statements have been made in good faith and are based on
reasonable assumptions,  there is no assurance that the expected results will be
achieved.  These statements include (without limitation) statements as to future
expectations,  beliefs, plans, strategies,  objectives,  events, conditions, and
financial




performance.  In  connection  with the "safe  harbor"  provisions of the Private
Securities  Litigation  Reform  Act of  1995,  the  company  is  providing  this
cautionary  statement  to identify  important  factors  that could cause  actual
results to differ materially from those anticipated.  The following factors,  in
addition to those discussed elsewhere in this release and in past and subsequent
securities  filings,  could  cause  actual  results  to differ  materially  from
management expectations as suggested by such "forward-looking" statements:

     o    the effects of the stipulation and agreement  relating to the AmerenUE
          Missouri electric excess earnings  complaint case and other regulatory
          actions, including changes in regulatory policy;
     o    changes in laws and other governmental actions, including monetary and
          fiscal policy;
     o    the  impact on the  company  of  current  regulations  related  to the
          opportunity for customers to choose  alternative  energy  suppliers in
          Illinois;
     o    the effects of increased competition in the future due to, among other
          things,  deregulation of certain aspects of the company's  business at
          both the state and federal levels;
     o    the  effects  of   participation   in  a  Federal  Energy   Regulatory
          Commission-approved  regional  transmission  organization,   including
          activities associated with the Midwest Independent System Operator;
     o    the  availability of fuel for the production of  electricity,  such as
          coal  and  natural  gas,  and  purchased  power  and  natural  gas for
          distribution, and the level and volatility of future market prices for
          such  commodities,  including  the  ability to recover  any  increased
          costs;
     o    the use of financial and derivative instruments;
     o    average rates for electricity in the Midwest;
     o    business and economic conditions;
     o    the  impact  of the  adoption  of new  accounting  standards  and  the
          application of appropriate technical accounting rules and guidance;
     o    interest rates and the availability of capital;
     o    actions of ratings agencies and the effects of such actions;
     o    weather conditions;
     o    generation plant construction, installation and performance;
     o    operation of nuclear power facilities and decommissioning costs;
     o    the  effects of  strategic  initiatives,  including  acquisitions  and
          divestitures;
     o    the impact of  current  environmental  regulations  on  utilities  and
          generating   companies  and  the   expectation   that  more  stringent
          requirements  will be introduced  over time,  which could  potentially
          have a negative financial effect;
     o    future wages and employee benefits costs, including changes in returns
          on benefit plan assets;
     o    disruptions  of  the  capital  markets  or  other  events  making  the
          company's access to necessary capital more difficult or costly;
     o    competition from other generating facilities, including new facilities
          that may be developed;
     o    difficulties  in  integrating  AmerenCILCO  with the  company's  other
          businesses;
     o    changes in the coal markets,  environmental  laws or  regulations,  or
          other factors adversely  impacting  synergy  assumptions in connection
          with the CILCORP Inc. acquisition;
     o    cost  and  availability  of  transmission   capacity  for  the  energy
          generated  by the  company's  generating  facilities  or  required  to
          satisfy energy sales made by the company; and
     o    legal and administrative proceedings.
                                      # # #








                            AMEREN CORPORATION (AEE)
                        CONSOLIDATED OPERATING STATISTICS


                                                           Three Months Ended               Nine Months Ended
                                                            September 30,                     September 30,
                                                   -----------------------------      ----------------------------
                                                          2003             2002              2003             2002
                                                   ------------     ------------      ------------     ------------
                                                                                             
Electric Sales - KWH (in millions):
       Residential                                       5,488            5,229             13,706           12,859
       Commercial                                        5,256            5,024             14,172           13,233
       Industrial                                        4,743            3,262             13,175            9,448
       Wholesale                                         2,418            2,507              6,671            6,657
       Other                                                73               69                225              204
                                                   ------------     ------------      -------------    -------------
         Native                                         17,978           16,091             47,949           42,401
       Interchange sales                                 2,145            1,467              6,566            6,555
       EEI                                               1,848            1,765              4,073            5,128
                                                   ------------     ------------      -------------    -------------
         Total                                          21,971           19,323             58,588           54,084

Electric Revenues - (in millions):
       Residential                                       $ 452            $ 437            $ 1,007            $ 974
       Commercial                                          362              345                880              824
       Industrial                                          221              157                558              400
       Wholesale                                            87               86                228              219
       Other                                                 6                6                 19               18
                                                   ------------     ------------      -------------    -------------
         Native                                          1,128            1,031              2,692            2,435
       Interchange sales                                    63               40                221              157
       EEI                                                  51               48                111              156
       Other                                                24               16                 66               64
                                                   ------------     ------------      -------------    -------------
         Total                                           1,266            1,135              3,090            2,812

Power Supply  (%):
      Fossil                                              77.0             78.9               77.2             74.3
      Nuclear                                             11.0             12.4               11.9             12.4
      Hydro                                                0.6              1.1                0.9              1.7
      Purchased                                           11.4              7.6               10.0             11.6

Fuel Cost per KWH (cents)                                1.166            1.104              1.081            1.027
Gas Sales - MMBTU (in thousands)                         6,983            3,040             50,745           25,818

                                                 September 30,     December 31,
                                                          2003             2002
                                                 --------------    -------------
Common Stock:
       Shares outstanding (in millions)                  162.3            154.1
       Book value per share                             $26.70           $24.26

Capitalization Ratios:
       Common equity                                     48.1%            51.6%
       Preferred stock                                    2.4%             2.6%
       Debt, net of cash                                 49.5%            45.8%











                            AMEREN CORPORATION (AEE)
                           CONSOLIDATED BALANCE SHEET
                            (Unaudited, in millions)

                                                                                      September 30,      December 31,
                                                                                          2003              2002
- ---------------------------------------------------------------------------------------------------------------------
                                ASSETS
- ---------------------------------------------------------------------------------------------------------------------
                                                                                           
Current Assets:
          Cash and cash equivalents                                             $              100   $          628
          Accounts receivable - trade                                                          362              266
          Unbilled revenue                                                                     184              176
          Miscellaneous accounts and notes receivable                                          131               44
          Materials and supplies, at average cost                                              476              299
          Other current assets                                                                  57               39
                                                                                -------------------  ---------------
            Total current assets                                                             1,310            1,452
                                                                                -------------------  ---------------
Property and Plant, net                                                                     10,152            8,840
Investments and Other Non-Current Assets:
          Investments                                                                          166               38
          Nuclear decommissioning trust fund                                                   195              172
          Goodwill and other intangibles, net                                                  630                -
          Other assets                                                                         317              307
                                                                                -------------------  ---------------
            Total investments and other assets                                               1,308              517
                                                                                -------------------  ---------------
Regulatory Assets                                                                              767              690
- --------------------------------------------------------------------------------------------------------------------
TOTAL ASSETS                                                                    $           13,537   $       11,499
====================================================================================================================

                 LIABILITIES AND STOCKHOLDERS' EQUITY
- --------------------------------------------------------------------------------------------------------------------
Current Liabilities:
          Current maturities of long-term debt                                  $              499   $          339
          Short-term debt                                                                        3              271
          Accounts and wages payable                                                           275              369
          Asset retirement obligations                                                           4                -
          Taxes accrued                                                                        231               45
          Other current liabilities                                                            237              177
                                                                                -------------------  ---------------
            Total current liabilities                                                        1,249            1,201
                                                                                -------------------  ---------------
Long-term Debt, Net                                                                          4,046            3,433
Preferred Stock Subject to Mandatory Redemption                                                 21                -
Deferred Credits and Other Non-Current Liabilities:
          Accumulated deferred income taxes, net                                             1,993            1,707
          Accumulated deferred investment tax credits                                          153              149
          Regulatory liabilities                                                               133              136
          Asset retirement obligations                                                         408              174
          Accrued pension liabilities                                                          527              377
          Other deferred credits and liabilities                                               439              272
                                                                                -------------------  ---------------
            Total deferred credits and other liabilities                                     3,653            2,815
                                                                                -------------------  ---------------
Preferred Stock Not Subject to Mandatory Redemption                                            213              193
Minority Interest in Consolidated Subsidiaries                                                  21               15
Stockholders' Equity:
          Common stock                                                                           2                2
          Other paid-in capital, principally premium on common stock                         2,528            2,203
          Retained earnings                                                                  1,917            1,739
          Accumulated other comprehensive income (loss)                                       (103)             (93)
          Other                                                                                (10)              (9)
                                                                                -------------------  ---------------
            Total stockholders' equity                                                       4,334            3,842
- ---------------------------------------------------------------------------------------------------  ---------------
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY                                      $           13,537   $       11,499
====================================================================================================================








                               AMEREN CORPORATION (AEE)
                           CONSOLIDATED STATEMENT OF INCOME
                  (Unaudited) (In millions, except per share amounts)
                                                                                         Three Months Ended       Nine Months Ended
                                                                                            September 30,           September 30,
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                          2003        2002         2003        2002
- ------------------------------------------------------------------------------------------------------------------------------------
                                                                                                            
Operating Revenues:
- ------------------------------------------------------------------------------------------------------------------------------------
            Electric                                                                   $ 1,266     $ 1,135      $ 3,090     $ 2,812
            Gas                                                                             82          30          450         202
            Other                                                                            2           1            6           4
                                                                                       --------    --------     --------    --------
                Total operating revenues                                                 1,350       1,166        3,546       3,018

Operating Expenses:
- ------------------------------------------------------------------------------------------------------------------------------------
            Fuel and purchased power                                                       330         248          793         655
            Gas purchased for resale                                                        54          17          326         129
            Other operations and maintenance                                               302         278          901         835
            Coal contract settlement                                                       (51)          -          (51)          -
            Depreciation and amortization                                                  132         108          388         321
            Taxes other than income taxes                                                   83          74          238         211
                                                                                       --------    --------     --------    --------
                Total operating expenses                                                   850         725        2,595       2,151
                                                                                       --------    --------     --------    --------
Operating Income                                                                           500         441          951         867
- ------------------------------------------------------------------------------------------------------------------------------------

Other Income and (Deductions):
- ------------------------------------------------------------------------------------------------------------------------------------
           Allowance for equity funds used during construction                               1           1            2           3
           Miscellaneous, net -
              Miscellaneous income                                                           3           5           14          13
              Miscellaneous expense                                                         (3)         (3)         (14)        (46)
                                                                                       --------    --------     --------    --------
                Total other income and (deductions)                                          1           3            2         (30)
                                                                                       --------    --------     --------    --------
Interest Charges and Preferred Dividends:
- ------------------------------------------------------------------------------------------------------------------------------------
            Interest                                                                        70          57          208         162
            Allowance for borrowed funds used during construction                           (1)         (1)          (4)         (4)
            Preferred dividends of subsidiaries                                              3           3            8           9
                                                                                       --------    --------     --------    --------
                Net interest charges and preferred dividends                                72          59          212         167
                                                                                       --------    --------     --------    --------
Income Before Income Taxes and Cumulative Effect of Change in Accounting Principle         429         385          741         670
- ------------------------------------------------------------------------------------------------------------------------------------

Income Taxes                                                                               154         145          273         256
                                                                                       --------    --------     --------    --------
Income Before Cumulative Effect of Change in Accounting Principle                          275         240          468         414
- ------------------------------------------------------------------------------------------------------------------------------------

Cumulative Effect of Change in Accounting Principle, Net of Income Taxes                     -           -           18           -
- ------------------------------------------------------------------------------------------------------------------------------------

Net Income                                                                             $   275     $   240      $   486     $   414
====================================================================================================================================

Earnings per Common Share - Basic:
   Income before cumulative effect of change in accounting principle                   $  1.70     $  1.64      $  2.91     $  2.88
   Cumulative effect of change in accounting principle, net of income taxes                  -           -         0.11           -
                                                                                       --------    --------     --------    --------
   Net income                                                                          $  1.70     $  1.64      $  3.02     $  2.88
====================================================================================================================================

Earnings per Common Share - Diluted:
   Income before cumulative effect of change in accounting principle                   $  1.70     $  1.63      $  2.91     $  2.87
   Cumulative effect of change in accounting principle, net of income taxes                  -           -         0.11           -
                                                                                       --------    --------     --------    --------
   Net income                                                                          $  1.70     $  1.63      $  3.02     $  2.87
====================================================================================================================================

Average Common Shares Outstanding                                                        161.8       146.7        160.7       143.6
====================================================================================================================================






                                   AMEREN CORPORATION (AEE)
                             CONSOLIDATED STATEMENT OF CASH FLOWS
                                   (Unaudited, in millions)

                                                                                                  Nine Months Ended
                                                                                                    September 30,
                                                                                                ----------------------
                                                                                                  2003          2002
- ----------------------------------------------------------------------------------------------------------------------
                                                                                                      
Cash Flows From Operating Activities:
- ----------------------------------------------------------------------------------------------------------------------
   Net Income                                                                                      $ 486        $ 414
   Adjustments to reconcile net income to net cash
     provided by operating activities:
        Cumulative effect of change in accounting principle                                          (18)           -
        Depreciation and amortization                                                                388          321
        Amortization of nuclear fuel                                                                  25           25
        Amortization of debt issuance costs and premium/discounts                                      8            6
        Allowance for funds used during construction                                                  (6)          (7)
        Deferred income taxes, net                                                                    30           11
        Deferred investment tax credits, net                                                          (9)          (6)
        Coal contract settlement                                                                     (45)           -
        Other                                                                                         (8)           5
        Changes in assets and liabilities, excluding the effects of the acquisitions:
                 Receivables, net                                                                     17          (49)
                 Materials and supplies                                                              (69)          15
                 Accounts and wages payable                                                         (171)        (217)
                 Taxes accrued                                                                       167          214
                 Assets, other                                                                        (2)         (16)
                 Liabilities, other                                                                   59           17
                                                                                                   ------       ------
Net cash provided by operating activities                                                            852          733
- ----------------------------------------------------------------------------------------------------------------------

Cash Flows From Investing Activities:
- ----------------------------------------------------------------------------------------------------------------------
    Construction expenditures                                                                       (457)        (565)
    Acquisitions, net of cash acquired                                                              (489)           -
    Allowance for funds used during construction                                                       6            7
    Nuclear fuel expenditures                                                                         (2)         (25)
    Other                                                                                              4            1
                                                                                                   ------       ------
Net cash used in investing activities                                                               (938)        (582)

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

Cash Flows From Financing Activities:
- ----------------------------------------------------------------------------------------------------------------------
    Dividends on common stock                                                                       (308)        (279)
    Capital issuance costs                                                                           (13)         (35)
    Redemptions -
        Nuclear fuel lease                                                                           (38)           -
        Short-term debt                                                                             (268)        (635)
        Long-term debt                                                                              (648)        (158)
        Preferred stock                                                                               (1)         (41)
    Issuances -
        Common stock                                                                                 336          635
        Nuclear fuel lease                                                                             -           31
        Long-term debt                                                                               498          893
                                                                                                   ------       ------
Net cash provided by (used in) financing activities                                                 (442)         411

- ----------------------------------------------------------------------------------------------------------------------
Net Change In Cash and Cash Equivalents                                                             (528)         562
Cash and Cash Equivalents at Beginning of Year                                                       628           67
- ----------------------------------------------------------------------------------------------------------------------

Cash and Cash Equivalents at End of Period                                                         $ 100        $ 629
=======================================================================================================================