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 FIRST QUARTER 2004 EARNINGS
                        Reaffirms 2004 Earnings Guidance

     St. Louis,  Mo.,  April 29,  2004---Ameren  Corporation  (NYSE:  AEE) today
announced  first quarter 2004 net income of $97 million,  or 55 cents per share,
compared  to first  quarter  2003 net  income of $101  million,  or 63 cents per
share.  Net income in the first three months of last year  included an after-tax
gain of $18  million,  or 11  cents  per  share,  due to the  adoption  of a new
accounting standard related to the recognition of asset retirement  obligations.
Income in the first quarter of 2003 before the cumulative  effect of this change
in accounting principle was $83 million, or 52 cents per share.

     "Despite milder winter weather, we were able to produce solid earnings this
quarter.  Excluding the 2003 gain associated  with the new accounting  standard,
2004 first  quarter  earnings  were up over first  quarter  2003,"  said Gary L.
Rainwater,   chairman,   chief   executive   officer  and  president  of  Ameren
Corporation.  "The CILCORP  acquisition,  emission  credit  sales,  a recovering
economy and our focus on cost control  positively  affected  2004 first  quarter
earnings.  These benefits more than offset the negative effects of milder winter
weather,  higher fuel and  purchased  power  costs,  weaker  energy  markets and
earnings per share dilution resulting from increased common shares outstanding."

     Revenues  in the first  quarter  of 2004  increased  $108  million  to $1.2
billion,  compared to the same period in 2003.  An  additional  month of CILCORP
Inc. sales in 2004,  resulting  from the completion of that  acquisition on Jan.
31, 2003,  increased revenues by $105 million.  In addition,  improving economic
conditions and higher sales to customers in the deregulated Illinois marketplace
increased total revenues as industrial and  weather-sensitive  commercial  sales
rose 4 percent and 1 percent,  respectively,  during the quarter.  Revenues also
benefited  from emission  credit sales that totaled $15 million  during the 2004
first quarter versus approximately $1 million in the prior-year period.

                                    - more -





Add One

     First  quarter 2004 revenue  gains were  partially  offset by the impact of
milder winter weather that reduced heating demand. In the first quarter of 2004,
heating degree days in Ameren's service  territory fell  approximately 9 percent
from the year-ago  period.  Interchange  electric  revenues  also  decreased $25
million in the first  quarter of 2004,  as  compared to the same period in 2003,
due to lower power prices and reduced  power plant  availability.  "As expected,
energy market conditions,  though solid in the first quarter of 2004, were below
the exceptionally strong first quarter of 2003," added Mr. Rainwater.

     Fuel and  purchased  power  expenses  increased  $39  million  in the first
quarter  of 2004,  versus  the same  period a year ago,  principally  due to the
additional month of CILCORP's operations in 2004, sales growth and less low-cost
power plant availability.

     Other  operations  and  maintenance  expenses  increased $14 million in the
first  quarter of 2004,  as  compared to 2003.  However,  other  operations  and
maintenance  expense  increased  approximately  $15  million  as a result  of an
additional month of CILCORP ownership in the current period.

     The company's  proposed  acquisition  from Dynegy Inc.  (NYSE:  DYN) of the
stock of  Decatur,  Ill.-based  Illinois  Power  and a 20  percent  interest  in
Electric Energy,  Inc. (EEI) continues to move forward in the regulatory  review
process. "In early February,  we announced the signing of a definitive agreement
to purchase  Illinois  Power and an increased  interest in EEI in a  transaction
valued at $2.3 billion," noted Mr.  Rainwater.  "In late March, we completed the
initial filings required for regulatory  approval.  This acquisition  remains on
target to close by the end of this year."

     Warner L. Baxter,  executive  vice  president and chief  financial  officer
added, "Following our announcement of the acquisition,  we quickly moved to sell
common stock,  generating proceeds of approximately $850 million.  This offering
was a  conservative  and  prudent  move to secure a  significant  portion of the
equity  financing  planned for the Illinois Power  transaction.  In total,  that
equity  financing  is expected  to equal at least 50 percent of the  transaction
value.  The  additional  shares issued in this offering  reduced  earnings by an
estimated 3 cents per share in the first quarter of 2004 since these shares were
issued  prior  to the  close  of  this  transaction.  However,  we  expect  this
acquisition  to be  accretive  to earnings by 5 to 10 cents per share in each of
the first two years after closing and to provide  significant,  long-term  value
for all of our stakeholders."

                                    - more -






Add Two

     Ameren  also  announced  today  that the  company is  reaffirming  its 2004
guidance for earnings per share of between  $2.75 and $2.95 per share.  The 2004
estimate  includes the impact of common shares  already issued to partially fund
the Illinois  Power  acquisition,  but excludes any  potential  earnings  impact
resulting from the Illinois Power  acquisition or potential further common stock
issuances  for this  transaction.  The  company's  guidance is subject to, among
other things, plant operations,  weather conditions,  energy market and economic
conditions,  unusual or otherwise unexpected gains or losses and other risks and
uncertainties  outlined in the company's  Forward-Looking  Statements section of
this release.

     Ameren will conduct a conference  call for financial  analysts at 9:00 a.m.
(Central Time) on Thursday, April 29, to discuss first quarter 2004 earnings and
other matters relating to the company.  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 "Q1 2004  Earnings  Conference  Call," then the
appropriate  audio link.  A slide  presentation  is also  available  on Ameren's
website that reconciles earnings per share between the first quarter of 2003 and
the first quarter of 2004. To access this  presentation  simply follow the links
for the  webcast,  and then  click on the  link for the  presentation,  which is
provided in a .pdf format. 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),  April 29, until May 6 by
dialing,  U.S. (800) 428-6051;  international  (973) 709-2089,  and entering the
number: 350682.

     With  assets  of $14.6  billion,  Ameren  owns a  diverse  mix of  electric
generating plants strategically located in its Midwest market with a capacity of
more than 14,600  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 closing and timing of Ameren's  acquisition  of Illinois  Power and the
     impact of any  conditions  imposed by regulators  in connection  with their
     approval thereof;
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 policies;
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;  weather
     conditions;  generation plant  construction,  installation and performance;
     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;  difficulties  in  integrating  AmerenCILCO  and Illinois
     Power, if consummated, 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 and Illinois Power acquisitions;
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;
o    and legal and administrative proceedings.

                                      # # #






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

                                                                                        March 31,        December 31,
                                                                                           2004              2003
- ------------------------------------------------------------------------------------------------------------------------
                                ASSETS
- ------------------------------------------------------------------------------------------------------------------------
                                                                                                 
Current Assets:
         Cash and cash equivalents                                                  $              633  $           111
         Accounts receivable - trade                                                               326              326
         Unbilled revenue                                                                          199              221
         Miscellaneous accounts and notes receivable                                                63              126
         Materials and supplies, at average cost                                                   412              487
         Other current assets                                                                       54               46
                                                                                    ------------------- ----------------
           Total current assets                                                                  1,687            1,317
                                                                                    ------------------- ----------------
Property and Plant, net                                                                         10,969           10,920
Investments and Other Non-Current Assets:
         Investments in leveraged leases                                                           161              164
         Nuclear decommissioning trust fund                                                        218              212
         Goodwill and other intangibles, net                                                       561              574
         Other assets                                                                              344              320
                                                                                    ------------------- ----------------
           Total investments and other non-current assets                                        1,284            1,270
                                                                                    ------------------- ----------------
Regulatory Assets                                                                                  701              729
- ------------------------------------------------------------------------------------------------------------------------

TOTAL ASSETS                                                                        $           14,641   $        14,236
- ------------------------------------------------------------------------------------------------------------------------
                 LIABILITIES AND STOCKHOLDERS' EQUITY
- ------------------------------------------------------------------------------------------------------------------------
Current Liabilities:
         Current maturities of long-term debt                                       $              331   $          498
         Short-term debt                                                                             2              161
         Accounts and wages payable                                                                249              480
         Taxes accrued                                                                             182              103
         Other current liabilities                                                                 252              215
                                                                                    ------------------- ----------------
           Total current liabilities                                                             1,016            1,457
                                                                                    ------------------- ----------------
Long-term Debt, Net                                                                              4,068            4,070
Preferred Stock of Subsidiary Subject to Mandatory Redemption                                       21               21
Deferred Credits and Other Non-Current Liabilities:
         Accumulated deferred income taxes, net                                                  1,802            1,853
         Accumulated deferred investment tax credits                                               148              151
         Regulatory liabilities                                                                    832              824
         Asset retirement obligations                                                              419              413
         Accrued pension and other postretirement benefits                                         741              699
         Other deferred credits and liabilities                                                    186              190
                                                                                    ------------------- ----------------
           Total deferred credits and other non-current liabilities                              4,128            4,130
                                                                                    ------------------- ----------------
Preferred Stock of Subsidiaries Not Subject to Mandatory Redemption                                182              182
Minority Interest in Consolidated Subsidiaries                                                      23               22
Stockholders' Equity:
         Common stock                                                                                2                2
         Other paid-in capital, principally premium on common stock                              3,425            2,552
         Retained earnings                                                                       1,834            1,853
         Accumulated other comprehensive income (loss)                                             (44)             (44)
         Other                                                                                     (14)              (9)
                                                                                    ------------------- ----------------
           Total stockholders' equity                                                            5,203            4,354
- ------------------------------------------------------------------------------------------------------- ----------------
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY                                          $           14,641  $        14,236
- ------------------------------------------------------------------------------------------------------------------------






                          AMEREN CORPORATION (AEE)
                        CONSOLIDATED STATEMENT OF INCOME
               (Unaudited) (In millions, except per share amounts)
                                                                                            Three Months Ended
                                                                                                 March 31,
                                                                                        --------------------------
                                                                                              2004           2003
- --------------------------------------------------------------------------------------------------------------------
                                                                                               
Operating Revenues:
- --------------------------------------------------------------------------------------------------------------------
        Electric                                                                          $    913       $    856
        Gas                                                                                    301            250
        Other                                                                                    2              2
                                                                                          --------       --------
           Total operating revenues                                                          1,216          1,108


Operating Expenses:
- --------------------------------------------------------------------------------------------------------------------
        Fuel and purchased power                                                               271            232
        Gas purchased for resale                                                               213            181
        Other operations and maintenance                                                       306            292
        Depreciation and amortization                                                          130            124
        Taxes other than income taxes                                                           80             78
                                                                                          --------       --------
           Total operating expenses                                                          1,000            907
                                                                                          --------       --------
Operating Income                                                                               216            201
- --------------------------------------------------------------------------------------------------------------------
Other Income and (Deductions):
- --------------------------------------------------------------------------------------------------------------------
        Miscellaneous income                                                                     8              6
        Miscellaneous expense                                                                   (1)            (3)
                                                                                          --------       --------
           Total other income and (deductions)                                                   7              3
                                                                                          --------       --------
Interest Charges and Preferred Dividends:
- --------------------------------------------------------------------------------------------------------------------
        Interest                                                                                64             66
        Preferred dividends of subsidiaries                                                      3              3
                                                                                          --------       --------
           Net interest charges and preferred dividends                                         67             69
                                                                                          --------       --------
Income Before Income Taxes and Cumulative Effect of Change in Accounting Principle             156            135
- -----------------------------------------------------------------------------------------------------------------
Income Taxes                                                                                    59             52
                                                                                          --------       --------
Income Before Cumulative Effect of Change in Accounting Principle                               97             83
- -----------------------------------------------------------------------------------------------------------------
Cumulative Effect of Change in Accounting Principle                                              -             18
- -----------------------------------------------------------------------------------------------------------------
Net Income                                                                                $     97       $    101
====================================================================================================================

Earnings per Common Share - Basic and Diluted:
   Income before cumulative effect of change in accounting principle                      $   0.55       $   0.52
   Cumulative effect of change in accounting principle, net of income taxes                      -           0.11
                                                                                          --------       --------
Earnings per Common Share - Basic and Diluted                                             $   0.55       $   0.63
                                                                                          --------       --------
Average Common Shares Outstanding                                                            174.3          158.9
====================================================================================================================







                                  AMEREN CORPORATION (AEE)
                             CONSOLIDATED STATEMENT OF CASH FLOWS
                                   (Unaudited, in millions)
                                                                                                  Three Months Ended
                                                                                                       March 31,
                                                                                                  -------------------
                                                                                                  2004          2003
- ---------------------------------------------------------------------------------------------------------------------------
                                                                                               

Cash Flows From Operating Activities:
   Net income                                                                                     $   97       $  101
   Adjustments to reconcile net income to net cash
    provided by operating activities:
       Cumulative effect of change in accounting principle                                             -          (18)
       Depreciation and amortization                                                                 130          124
       Amortization of nuclear fuel                                                                    8            7
       Amortization of debt issuance costs and premium/discounts                                       3            2
       Deferred income taxes, net                                                                    (24)           3
       Deferred investment tax credits, net                                                           (3)          (3)
       Coal contract settlement                                                                        9            -
       Changes in assets and liabilities, excluding the effects of the acquisitions:
               Receivables, net                                                                       37           13
               Materials and supplies                                                                 75           44
               Accounts and wages payable                                                           (195)        (186)
               Taxes accrued                                                                          79           68
               Assets, other                                                                         (15)           5
               Liabilities, other                                                                     55           73
               Other                                                                                 (12)          (7)
                                                                                                 -------       ------
Net cash provided by operating activities                                                            244          226
- ---------------------------------------------------------------------------------------------------------------------------
Cash Flows From Investing Activities:
- ---------------------------------------------------------------------------------------------------------------------------
       Construction expenditures                                                                    (165)        (144)
       Acquisitions, net of cash acquired                                                              -         (488)
       Nuclear fuel expenditures                                                                      (3)           -
       Other                                                                                           7            3
                                                                                                 -------       ------
Net cash used in investing activities                                                               (161)        (629)
- ---------------------------------------------------------------------------------------------------------------------------

Cash Flows From Financing Activities:
- ---------------------------------------------------------------------------------------------------------------------------
       Dividends on common stock                                                                    (116)        (102)
       Capital issuance costs                                                                        (22)         (10)
       Redemptions, repurchases and maturities:
          Nuclear fuel lease                                                                         (67)          (2)
          Short-term debt                                                                           (159)        (255)
          Long-term debt                                                                            (100)         (31)
       Issuances:
          Common stock                                                                               903          285
          Long-term debt                                                                               -          184
                                                                                                 -------       ------
Net cash provided by financing activities                                                            439           69
- ---------------------------------------------------------------------------------------------------------------------------

Net Change In Cash and Cash Equivalents                                                              522         (334)
Cash and Cash Equivalents at Beginning of Year                                                       111          628
- ---------------------------------------------------------------------------------------------------------------------------

Cash and Cash Equivalents at End of Period                                                       $   633       $  294
===========================================================================================================================








                            AMEREN CORPORATION (AEE)
                        CONSOLIDATED OPERATING STATISTICS



                                                      Three Months Ended
                                                           March 31,
                                                  -------------------------
                                                     2004             2003
                                                  -------------------------
                                                    
Electric Sales - KWH (in millions):
       Residential                                   4,943            4,750
       Commercial                                    4,819            4,410
       Industrial                                    4,323            3,903
       Wholesale                                     2,765            2,286
       Other                                            83               76
                                                  --------       ----------
         Native                                     16,933           15,425
       Interchange                                   2,150            2,421
       EEI                                             877              769
                                                 ---------       ----------
         Total                                      19,960           18,615


Electric Revenues - (in millions):
       Residential                               $     286       $      273
       Commercial                                      241              222
       Industrial                                      164              141
       Wholesale                                        95               75
       Other                                             6                6
                                                 ---------       ----------
         Native                                        792              717
       Interchange                                      76              101
       EEI                                              15               18
       Other                                            30               20
                                                 ---------       ----------
         Total                                         913              856
                                                 ---------       ----------
Power Supply  (%):
      Fossil                                          79.0             80.8
      Nuclear                                         10.0             11.5
      Hydro                                            1.7              0.6
      Purchased                                        9.3              7.1
Fuel Cost per KWH (cents)                            1.075            0.990
Gas Sales - MMBTU (in thousands)                    35,036           27,065


                                                   March 31,     December 31,
                                                    2004             2003
                                                 ------------    ------------
Common Stock:
       Shares outstanding (in millions)              182.5            162.9
       Book value per share                         $28.51           $26.73

Capitalization Ratios:
       Common equity                                  56.7%            47.5%
       Preferred stock                                 2.0%             2.0%
       Debt, net of cash                              41.3%            50.5%