<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                    FORM 10-Q

[X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANG
    ACT OF 1934

    For Quarterly Period Ended June 30, 2000

[ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
    ACT OF 1934

    For The Transition Period From           to

                         Commission file number 1-3672.

                     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
             (Exact name of registrant as specified in its charter)

           Illinois                                               37-0211380
(State or other jurisdiction of                               (I.R.S. Employer
incorporation or organization)                               Identification No.)


               607 East Adams Street, Springfield, Illinois 62739
              (Address of principal executive offices and Zip Code)


                         Registrant's telephone number,
                       including area code: (217) 523-3600


     Indicate  by check mark  whether the  registrant  (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days.


                          Yes     X  .      No    .
                                ------         ----


Shares  outstanding of each of  registrant's  classes of common stock as of July
  31, 2000:  Common  Stock,  no par value,  held by Ameren  Corporation  (parent
  company of Registrant) - 25,452,373


<PAGE>


                     Central Illinois Public Service Company

                                      Index

                                                                     Page No.

Part I      Financial Information (Unaudited)

            Management's Discussion and Analysis                         2

            Quantitative and Qualitative Disclosures
            About Market Risk                                            5

            Balance Sheet
            - June 30, 2000 and December 31, 1999                        8

            Statement of Income
            - Three months, six months and 12 months ended
               June 30, 2000 and 1999                                    9

            Statement of Cash Flows
            - Six months ended June 30, 2000 and 1999                   10

            Notes to Financial Statements                               11


Part II     Other Information                                           14


<PAGE>


9
                    PART I. FINANCIAL INFORMATION (UNAUDITED)

MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF
OPERATIONS

OVERVIEW

Central  Illinois  Public Service  Company  (AmerenCIPS or the  Registrant) is a
subsidiary of Ameren  Corporation  (Ameren),  a holding company registered under
the Public Utility Holding Company Act of 1935 (PUHCA).  In December 1997, Union
Electric Company  (AmerenUE) and CIPSCO  Incorporated  (CIPSCO) combined to form
Ameren,  with  AmerenUE and CIPSCO's  subsidiaries,  the  Registrant  and CIPSCO
Investment Company (CIC), becoming subsidiaries of Ameren (the Merger).

On May 1,  2000,  following  the  receipt  of all  required  State  and  Federal
regulatory approvals,  the Registrant transferred its electric generating assets
and liabilities,  at historical net book value, to a newly created  nonregulated
company,  AmerenEnergy  Generating Company (Generating Company), a subsidiary of
AmerenEnergy Resources Company (Resources Company), a wholly-owned subsidiary of
Ameren (the  Transfer).  Discussion  below under Results of Operations  reflects
that as a result of the Transfer,  interchange  sales from May 1, 2000 and sales
under  certain  wholesale   contracts  are  no  longer  being  included  in  the
Registrant's  operating  revenues  and that  operating  expenses  include  those
expenses  it  incurs  under  its  traditional   transmission   and  distribution
operations,  as well as purchased power under an electric power supply agreement
with  Resources  Company's  newly  created  marketing  subsidiary.  See Electric
Industry  Restructuring  and Note 1 under  Notes  to  Financial  Statements  for
further discussion.

The following  discussion and analysis  should be read in  conjunction  with the
Notes  to  Financial  Statements  beginning  on page  11,  and the  Management's
Discussion and Analysis of Financial Condition and Results of Operations (MD&A),
the Audited Financial Statements and the Notes to Financial Statements appearing
in the Registrant's 1999 Form 10-K.

RESULTS OF OPERATIONS

Earnings
Second  quarter 2000  earnings of $19 million were  comparable  to 1999's second
quarter earnings.  Earnings for the six months ended June 30, 2000 increased $11
million  from the  year-ago  period to $44  million.  Earnings for the 12 months
ended June 30, 2000 were $61 million, an $18 million decrease from the preceding
12-month period.

Earnings  fluctuated due to many conditions,  primarily:  sales growth,  weather
variations,  electric  rate  reductions,  the  Transfer,  a gas  rate  increase,
competitive  market forces,  fluctuating  operating  costs,  changes in interest
expense,  changes in income and property  taxes and  nonrecurring  charges for a
targeted employee separation plan and for coal contract termination payments.

The  significant  items  affecting  revenues,  costs  and  earnings  during  the
three-month,  six-month  and 12-month  periods  ended June 30, 2000 and 1999 are
detailed below.

Electric Operations

Electric Operating Revenues      Variations for periods ended June 30, 2000
                                     from comparable prior-year periods
--------------------------------------------------------------------------------
(Millions of Dollars)           Three Months      Six Months      Twelve Months
                                ------------      ----------      -------------
--------------------------------------------------------------------------------
Rate variations                  $    -             $    -          $   (1)
Effect of abnormal weather            -                 (2)             (4)
Growth and other                      3                 19              21
Interchange sales                   (34)                (1)             57
--------------------------------------------------------------------------------
                                 $  (31)            $   16          $   73
-------------------------------------------------------------------------------

Electric  revenues  for the three  months  ended June 30,  2000,  decreased  $31
million  compared to the prior three- month period primarily due to a 51 percent
decrease in interchange  sales. As a result of the Transfer,  interchange  sales
are now being recorded at Resources Company.

                                       -2-

<PAGE>

Electric revenues for the six months ended June 30, 2000,  increased $16 million
compared to the prior  six-month  period  primarily  due to  increases in native
sales of 21 percent. The increase in native sales was primarily due to increased
wholesale,  commercial  and  industrial  sales,  offset  in  part  by  decreased
interchange sales as a result of the Transfer.

Electric revenues for the 12 months ended June 30, 2000,  increased $73 million,
compared  to  the  same  prior  year  period,  primarily  due  to  increases  in
interchange  sales of 12 percent,  due to strong marketing efforts and increases
in native sales of 11 percent. The increase in native sales was primarily due to
increased wholesale and industrial sales.

<TABLE>
<CAPTION>

Fuel and Purchased Power                   Variations for periods ended June 30, 2000
                                              from comparable prior-year periods
-----------------------------------------------------------------------------------------
(Millions of Dollars)                 Three Months    Six Months         Twelve Months
                                      ------------    ----------         -------------
-----------------------------------------------------------------------------------------
Fuel:
<S>                                     <C>           <C>                  <C>
    Generation                          $  (30)       $  (19)              $  (10)
    Price                                   (2)           (6)                 (12)
    Generation efficiencies and other       (3)           (3)                  (8)
    Coal contract termination payments       -             -                   52
Purchased power                             47            66                   90
-----------------------------------------------------------------------------------------
                                        $   12        $   38               $  112
-----------------------------------------------------------------------------------------

</TABLE>

Fuel and purchased  power costs for the three and six months ended June 30, 2000
increased  $12  million  and $38  million,  respectively,  versus the prior year
periods,  primarily due to an overall net increase in  generation  and purchased
power resulting from higher native sales and higher  purchased power costs under
the  provisions  of the  Power  Supply  Agreement  entered  into  as part of the
Transfer, partially offset by lower fuel prices.

The $112 million  increase in fuel and  purchased  power costs for the 12 months
ended June 30, 2000 versus the  prior-year  period was  primarily  the result of
increased  purchased  power,  resulting  from  higher  sales  volume  and higher
purchased power costs under the provisions of the Power Supply Agreement entered
into as part of the Transfer, and coal contract termination payments,  partially
offset by lower fuel prices.

Gas Operations
Gas revenues for the  three-month  and  six-month  periods  ended June 30, 2000,
increased $4 million  compared to the year-ago  periods  primarily due to higher
gas costs recovered  through the Registrant's  purchased gas adjustment  clause,
partially  offset  by  decreased  retail  sales  of 7  percent  and  5  percent,
respectively. Gas revenues for the 12-month period ended June 30, 2000 increased
$13 million  compared to the same  year-ago  period  primarily due to a gas rate
increase which became  effective in February 1999 and higher gas costs recovered
through the Registrant's  purchased gas adjustment clause.  These increases were
partially offset by an 11 percent decline in retail sales, as well as a decrease
in off-system sales to others.

Gas  costs  for the  three-month  and  12-month  periods  ended  June 30,  2000,
increased  $3 million and $9  million,  respectively,  compared to the  year-ago
periods  primarily  due to higher gas prices,  partially  offset by lower retail
sales.

Other Operating Expenses
Other operating expense variations  reflected  recurring factors such as growth,
inflation,  the Transfer,  labor and benefit decreases,  in addition to a charge
for the targeted separation plan.

Other  operations  expenses  decreased $17 million and $15 million for the three
months and six months  ended June 30, 2000,  respectively,  compared to the same
year-ago  periods  primarily  due to lower  employee  benefit  costs,  a reduced
workforce and the Transfer, partially offset by increased professional services.
Other operations  expenses decreased $7 million for the 12 months ended June 30,
2000, compared to the same year-ago period, primarily due to a reduced workforce
and the  Transfer,  coupled with the fact that  expenses  for the twelve  months
ended  June 30,  1999  included  a  nonrecurring  pretax  charge  for a targeted
separation  plan  of $7  million.  These  decreases  were  partially  offset  by
increased  injuries and damages expenses based on claims experience and expenses
associated with deregulation in Illinois.

Maintenance  expenses  for the three  months and six months  ended June 30, 2000
decreased  $14  million  and $15  million,  respectively,  from  the  comparable
year-ago periods. These decreases were primarily the result of decreased

                                       -3-

<PAGE>

power plant maintenance and the Transfer. Maintenance expenses for the 12 months
ended June 30, 2000 increased $9 million from the comparable year-ago period due
to increased power plant maintenance offset in part by the Transfer.

Taxes
Income  taxes for the six months  ended June 30,  2000,  increased  $9  million,
primarily due to higher pretax income. Income taxes for the 12 months ended June
30, 2000, decreased $8 million, primarily due to lower pretax income.

Other  taxes  for the six  months  ended  June 30,  2000  increased  $3  million
primarily  due to  increased  property  taxes as a result  of  higher  estimated
assessment values.  Other taxes for the 12 months ended June 30, 2000, decreased
$2 million  primarily due to a decrease in gross receipt  taxes,  resulting from
the restructuring of the Illinois public utility tax whereby gross receipt taxes
are no longer recorded as electric  revenue and gross receipt tax expense.  This
decrease was partially offset by increased  property taxes as a result of higher
estimated assessment values.

Other Income and Deductions
For  the  three  months,   six  months  and  12  months  ended  June  30,  2000,
miscellaneous net increased $7 million, $7 million and $9 million, respectively,
compared to same year-ago  periods,  primarily due to interest  income earned on
the promissory note receivable from Generating  Company.  See Electric  Industry
Restructuring  and  Note 1 under  Notes  to  Financial  Statements  for  further
discussion of the promissory note.

Balance Sheet
Changes in accounts and wages payable,  taxes accrued,  other accounts and notes
receivable,  and other  current  assets  resulted  from the  timing  of  various
payments to taxing authorities and suppliers.

LIQUIDITY AND CAPITAL RESOURCES

Cash  provided by operating  activities  totaled $102 million for the six months
ended June 30, 2000, compared to $80 million during the same 1999 period.

Cash flows used in investing  activities totaled $20 million and $62 million for
the six  months  ended  June  30,  2000  and  1999,  respectively.  Construction
expenditures  for the six months ended June 30, 2000,  for  constructing  new or
improving  existing  facilities,  were $20  million.  Construction  expenditures
decreased from the prior period due to the effects of the Transfer. See Electric
Industry  Restructuring  and Note 1 under  Notes  to  Financial  Statements  for
further discussion.

Cash flows used in financing  activities  totaled $81 million for the six months
ended June 30, 2000,  compared to $10 million  during the same 1999 period.  The
Registrant's  principal  financing  activities  for  the  quarter  included  the
redemption of long-term debt, the payment of intercompany  notes payable and the
payment of dividends, partially offset by the issuance of long-term debt.

The Registrant  plans to continue  utilizing  short-term  debt to support normal
operations and other temporary requirements. The Registrant is authorized by the
Securities  and  Exchange  Commission  under PUHCA to have up to $250 million of
short-term  unsecured debt instruments  outstanding at any one time.  Short-term
borrowings  consist of bank loans  (maturities  generally on an overnight basis)
and commercial  paper  (maturities  generally  within 1 to 45 days). At June 30,
2000, the Registrant had committed bank lines of credit  aggregating $25 million
(all of which was  unused and  available  at such  date)  which  make  available
interim  financing  at  various  rates  of  interest  based on  LIBOR,  the bank
certificate of deposit rate or other options.  The lines of credit are renewable
annually at various dates  throughout the year. At June 30, 2000, the Registrant
had no outstanding short-term borrowings.

Also, the Registrant has the ability to borrow up to approximately  $950 million
from Ameren or AmerenUE through a regulated money pool agreement.  The regulated
money pool was established to coordinate and provide for certain short-term cash
and working capital requirements and is administered by Ameren Services Company,
another  subsidiary  of Ameren.  Interest  is  calculated  at  varying  rates of
interest  depending on the  composition  of internal  and external  funds in the
regulated  money pool.  At June 30,  2000,  the  Registrant  had $120 million of
intercompany  borrowings  outstanding  and $434  million  available  through the
regulated money pool.

The Registrant,  in the ordinary course of business,  explores  opportunities to
reduce  its costs in order to remain  competitive  in the  marketplace.  An area
where the Registrant  focuses its review includes,  but is not limited to, labor
costs. In the labor area, the Registrant has reached  agreements with all of the
Registrant's  major  collective  bargaining units which will permit it to manage
its labor costs and practices effectively in the future. The Registrant

                                       -4-

<PAGE>

also explores  alternatives  to  effectively  manage the size of its  workforce.
These  alternatives  include utilizing hiring freezes,  outsourcing and offering
employee separation packages.

Certain of these cost reduction alternatives could require nonrecurring payments
of employee separation benefits. Management is unable to predict which (if any),
and to what extent, these alternatives to reduce its overall cost structure will
be executed.  Management  is unable to determine  the impact of these actions on
the Registrant's future financial position, results of operations or liquidity.

ELECTRIC INDUSTRY RESTRUCTURING

In December 1997, the Governor of Illinois signed the Electric  Service Customer
Choice and Rate  Relief Law of 1997 (the Law)  providing  for  electric  utility
restructuring  in Illinois.  This  legislation  introduces  competition into the
supply of electric energy at retail in Illinois.

One of the major  provisions of the Law includes the phasing-in  through 2002 of
retail direct access, which allows customers to choose their electric generation
supplier.  The phase-in of retail direct  access began on October 1, 1999,  with
large  commercial and industrial  customers  principally  comprising the initial
group.  The customers in this group  represent  approximately  24 percent of the
Registrant's  total  sales.  As of June 30,  2000,  the impact of retail  direct
access  on  the  Registrant's  financial  condition,  results  of  operation  or
liquidity was immaterial.  Retail direct access will be offered to the remaining
commercial  and  industrial  customers on December 31, 2000,  and to residential
customers on May 1, 2002.

The Transfer
In conjunction with another provision of the Law, on May 1, 2000,  following the
receipt of all required State and Federal regulatory  approvals,  the Registrant
transferred its electric  generating  assets and liabilities,  at historical net
book value, to a newly created  nonregulated  company,  AmerenEnergy  Generating
Company (Generating Company), a subsidiary of AmerenEnergy  Resources Company, a
wholly-owned  subsidiary  of Ameren,  in  exchange  for a  promissory  note from
Generating  Company  in the  principal  amount of $552  million  and  Generating
Company  common stock.  The  promissory  note has a term of five years and bears
interest at 7 percent based on a 10-year  amortization.  The transferred  assets
represent a generating capacity of approximately 2,900 megawatts.  Approximately
45 percent of the Registrant's  employees were transferred to Generating Company
as a part of the transaction.

Also on May 1, 2000, an electric power supply agreement was entered into between
Generating  Company and a newly  created  nonregulated  affiliate,  AmerenEnergy
Marketing  Company  (Marketing  Company),  also  a  wholly-owned  subsidiary  of
Resources Company. On the same date,  Marketing Company entered into an electric
power supply agreement with the Registrant (Power Supply Agreement) to supply it
sufficient power to meet native load requirements. A portion of the capacity and
energy supplied by Generating Company to Marketing Company will be resold to the
Registrant  for  resale to  native  load  customers  at rates  specified  by the
Illinois Commerce Commission (which approximate the historical  regulatory rates
for generation) or to retail  customers  allowed choice of an electric  supplier
under state law at market based  prices.  This  agreement  expires  December 31,
2004.  In turn,  the  Registrant  will  bill  these  customers  at  rates  which
approximate the costs the Registrant incurs for its capacity and energy supplied
by Generating Company. For the two-month period ended June 30, 2000, $57 million
of  the  Registrant's  purchased  power  was  derived  under  the  Power  Supply
Agreement.

As  a  result  of  the  Transfer,  coupled  with  the  Power  Supply  Agreement,
prospectively  from May 1, 2000  through  December 31,  2004,  the  Registrant's
operating   revenues  will  include   revenues   derived  from  its  traditional
transmission and distribution operations,  as well as those revenues it receives
from its native load customers,  or new customers  allowed choice of an electric
supplier  under  state  law.  Sales  under  certain   wholesale   contracts  and
interchange  sales will no longer be  reflected  in  operating  revenues  of the
Registrant.  Instead,  those revenues will be recorded at Resources Company. The
Registrant's  operating expenses will include those expenses it incurs under its
traditional transmission and distribution operations, as well as purchased power
expenses incurred under the terms of the Power Supply Agreement.

In addition,  as a result of the Transfer,  the  Registrant  incurred a deferred
intercompany tax gain,  which resulted in an additional  deferred tax liability.
An intercompany  tax receivable with Generating  Company was established for the
deferred tax  liability.  This asset and liability will be amortized over twenty
years.  At  June  30,  2000,  the   Registrant's   deferred  tax  liability  and
intercompany tax receivable was $219 million.

                                       -5-

<PAGE>

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Market risk  represents the risk of changes in value of a financial  instrument,
derivative or non-derivative,  caused by fluctuations in market variables (e.g.,
interest rates, equity prices, commodity prices, etc.). The following discussion
of  Ameren's,   including  AmerenCIPS',   risk  management  activities  includes
"forward-looking"  statements  that  involve  risks  and  uncertainties.  Actual
results could differ  materially from those  projected in the  "forward-looking"
statements. Ameren handles market risks in accordance with established policies,
which may include entering into various derivative  transactions.  In the normal
course of  business,  Ameren also faces risks that are either  non-financial  or
non-quantifiable.  Such risks principally include business,  legal,  operational
and credit risk and are not represented in the following analysis.

Interest Rate Risk
The  Registrant  is exposed to market risk  through  changes in  interest  rates
through its  issuance  of both  long-term  and  short-term  variable-rate  debt,
commercial paper and auction rate preferred  stock.  The Registrant  manages its
interest rate exposure by controlling  the amount of these  instruments it holds
within its total  capitalization  portfolio  and by  monitoring  the  effects of
market changes in interest rates.

If interest rates increase one percentage point in 2001 as compared to 2000, the
Registrant's  interest  expense would  increase and net income would decrease by
approximately $1 million.  This amount has been determined using the assumptions
that the  Registrant's  outstanding  variable  rate debt,  commercial  paper and
auction market preferred stock as of June 30, 2000,  continued to be outstanding
throughout  2001,  and that the  average  interest  rates for these  instruments
increased  one  percentage  point over 2000.  The model  does not  consider  the
effects of the reduced  level of overall  economic  activity that would exist in
such an  environment.  In the event of a significant  change in interest  rates,
management  would likely take  actions to further  mitigate its exposure to this
market risk. However,  due to the uncertainty of the specific actions that would
be taken and their possible effects,  the sensitivity analysis assumes no change
in the Registrant's financial structure.

Commodity Price Risk
The  Registrant  is exposed to changes in market prices for natural gas and fuel
and  electricity.   With  regard  to  its  natural  gas  utility  business,  the
Registrant's  exposure to changing  market prices is in large part  mitigated by
the fact that the  Registrant  has a Purchased  Gas  Adjustment  Clause (PGA) in
place.  The PGA allows the  Registrant to pass on to its customers its prudently
incurred costs of natural gas.

While  the  Registrant  does not  have a  provision  similar  to the PGA for its
electric operations,  purchased power price risk is mitigated in part due to the
fact that the Registrant  has entered into a long-term  contract with a supplier
for purchased power (see Electric Industry  Restructuring and Note 1 under Notes
to Financial Statements for further discussion). With regard to the Registrant's
exposure to commodity price risk for purchased  power,  Ameren has established a
subsidiary,  AmerenEnergy,  Inc.  (AmerenEnergy),  whose primary  responsibility
includes  managing  market risks  associated with the changing market prices for
electricity purchased on behalf of the Registrant.

ACCOUNTING MATTERS

In June 1998, the Financial  Accounting  Standards Board (FASB) issued Statement
of  Financial  Accounting  Standards  (SFAS)  133,  "Accounting  for  Derivative
Instruments  and  Hedging  Activities."  SFAS  133  establishes  accounting  and
reporting  standards for derivative  instruments,  including certain  derivative
instruments embedded in other contracts, and for hedging activities and requires
recognition  of all  derivatives  as either assets or liabilities on the balance
sheet  measured  at fair  value.  In June 1999,  the FASB  issued  SFAS No. 137,
"Accounting for Derivative  Instruments and Hedging Activities - Deferral of the
Effective  Date of FASB  Statement No. 133," which delayed the effective date of
SFAS 133 to all fiscal  quarters of all fiscal years,  beginning  after June 15,
2000.  In June 2000,  the FASB  issued  SFAS No.  138,  "Accounting  for Certain
Derivative  Instruments  and Certain  Hedging  Activities  -an amendment of FASB
Statement No. 133," which amended certain accounting and reporting  standards of
SFAS 133. Management believes that adoption of SFAS 133 will not have a material
impact on the  Registrant's  financial  position or results of  operations  upon
adoption  based on the  derivative  instruments  that  existed at June 30, 2000.
However,  changing market conditions and the volume of future transactions which
fall within the scope of SFAS 133, as amended,  and the interpretations from the
FASB's  Derivative   Implementation  Group  could  change  management's  current
assessment.  As a result, SFAS 133, as amended, could increase the volatility of
the  Registrant's  future  earnings  and could be material  to the  Registrant's
financial position and results of operations upon adoption.

                                       -6-

<PAGE>

SAFE HARBOR STATEMENT

Statements made in this Form 10-Q 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,
financial  performance  and the Year 2000 Issue.  In  connection  with the "Safe
Harbor" provisions of the Private Securities  Litigation Reform Act of 1995, the
Registrant 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 report and
in the Annual  Report on Form 10-K for the fiscal year ended  December 31, 1999,
and in subsequent  securities filings,  could cause results to differ materially
from management expectations as suggested by such "forward-looking"  statements:
the  effects  of  regulatory  actions;  changes  in laws and other  governmental
actions;  the impact on the  Registrant  of current  regulations  related to the
phasing-in of the  opportunity for some customers to choose  alternative  energy
suppliers in Illinois;  the effects of increased  competition  in the future due
to, among other  things,  deregulation  of certain  aspects of the  Registrant's
business at both the State and Federal levels; future market prices for fuel and
purchased power,  electricity,  and natural gas,  including the use of financial
instruments; average rates for electricity in the Midwest; business and economic
conditions;  interest rates;  weather conditions;  fuel prices and availability;
generation plant performance; 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;  monetary  and fiscal  policies;  future  wages and
employee benefits costs; and legal and administrative proceedings.

                                       -7-

<PAGE>

<TABLE>
<CAPTION>

                     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                  BALANCE SHEET
                                    UNAUDITED
                                    ---------
                      (Thousands of Dollars, Except Shares)


                                                                 June 30,    December 31,
ASSETS                                                             2000         1999
------                                                          ----------   ----------
<S>                                                             <C>          <C>
Property and plant, at original cost:
   Electric                                                     $1,185,886   $2,422,002
   Gas                                                             271,062      267,909
                                                                ----------   ----------
                                                                 1,456,948    2,689,911
   Less accumulated depreciation and amortization                  637,627    1,260,582
                                                                ----------   ----------
                                                                   819,321    1,429,329
Construction work in progress                                        6,741       43,435
                                                                ----------   ----------
         Total property and plant, net                             826,062    1,472,764
                                                                ----------   ----------

Investments and other assets:
   Intercompany notes receivable                                   511,701         --
   Intercompany tax receivable                                     202,882         --
   Other                                                            17,684       17,722
                                                                ----------   ----------
         Total investments and other assets                        732,267       17,722
                                                                ----------   ----------


Current assets:
   Cash and cash equivalents                                        12,626       12,536
   Accounts receivable - trade (less allowance for doubtful
         accounts of $2,563 and $1,828, respectively)               49,288       48,703
   Unbilled revenue                                                 76,919       75,884
   Other accounts and notes receivable                              29,050       20,875
   Intercompany notes receivable                                    39,925         --
   Intercompany tax receivable                                      16,114         --
   Materials and supplies, at average cost -
      Fossil fuel                                                   14,160       47,291
      Other                                                          9,746       33,931
   Other                                                             6,768       10,387
                                                                ----------   ----------
         Total current assets                                      254,596      249,607
                                                                ----------   ----------
Regulatory assets:
   Deferred income taxes                                               364       21,520
   Other                                                             9,401       20,141
                                                                ----------   ----------
         Total regulatory assets                                     9,765       41,661
                                                                ----------   ----------
Total Assets                                                    $1,822,690   $1,781,754
                                                                ==========   ==========

CAPITAL AND LIABILITIES
Capitalization:
   Common stock, no par value, 45,000,000 shares authorized -
     25,452,373 shares outstanding                              $  120,033   $  120,033
   Retained earnings                                               422,385      414,345
                                                                ----------   ----------
         Total common stockholder's equity                         542,418      534,378
   Preferred stock not subject to mandatory redemption              80,000       80,000
   Long-term debt                                                  468,116      493,625
                                                                ----------   ----------
        Total capitalization                                     1,090,534    1,108,003
                                                                ----------   ----------
Current liabilities:
   Current maturity of long-term debt                               30,000       35,000
   Intercompany notes payable                                      120,350      132,900
   Accounts and wages payable                                      119,100       82,800
   Accumulated deferred income taxes                                19,618       22,621
   Taxes accrued                                                    22,858       32,145
   Other                                                            34,401       39,619
                                                                ----------   ----------
         Total current liabilities                                 346,327      345,085
                                                                ----------   ----------
Accumulated deferred income taxes                                  310,741      216,661
Accumulated deferred investment tax credits                         13,196       32,169
Regulatory liability                                                36,004       34,004
Other deferred credits and liabilities                              25,888       45,832
                                                                ----------   ----------
Total Capital and Liabilities                                   $1,822,690   $1,781,754
                                                                ==========   ==========

</TABLE>

See Notes to Financial Statements.

                                       -8-

<PAGE>

<TABLE>
<CAPTION>

                                               CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                                                          STATEMENT OF INCOME
                                                                       UNAUDITED
                                                               ---------
                                                        (Thousands of Dollars)


                                                  Three Months Ended        Six Months Ended       Twelve Months Ended
                                                       June 30,                 June 30,                June 30,
                                              -----------------------   ---------------------    ------------------------
                                                 2000         1999         2000        1999         2000         1999
                                                 ----         ----         ----        ----         ----         ----

 OPERATING REVENUES:
<S>                                           <C>          <C>          <C>         <C>          <C>          <C>
    Electric                                  $ 169,331    $ 200,336    $ 371,834   $ 355,576    $ 811,734    $ 739,050
    Gas                                          25,788       21,593       78,612      74,125      137,133      123,731
                                              ---------    ---------    ---------   ---------    ---------    ---------
 Total operating revenues                       195,119      221,929      450,446     429,701      948,867      862,781

 OPERATING EXPENSES:
    Operations
       Fuel and purchased power                  82,128       70,542      163,758     126,232      351,734      240,139
       Gas                                       12,446        9,752       44,160      43,002       74,510       65,497
       Other                                     28,450       45,581       71,446      85,979      176,089      183,305
                                              ---------    ---------    ---------   ---------    ---------    ---------
                                                123,024      125,875      279,364     255,213      602,333      488,941
    Maintenance                                  11,549       25,161       28,053      42,568       89,067       80,189
    Depreciation and amortization                15,236       19,449       36,586      40,189       76,954       77,078
    Income taxes                                 11,958       11,197       26,121      17,176       39,718       47,316
    Other taxes                                  11,167       10,266       22,403      19,865       42,851       44,684
                                              ---------    ---------    ---------   ---------    ---------    ---------
       Total operating expenses                 172,934      191,948      392,527     375,011      850,923      738,208

 OPERATING INCOME                                22,185       29,981       57,919      54,690       97,944      124,573

 OTHER INCOME AND (DEDUCTIONS):
    Allowance for equity funds used
       during construction                         --              7         --             1           (9)
                                                                                                                    (32)
    Miscellaneous, net                            7,439          725        7,816       1,081        8,765         (163)
                                              ---------    ---------    ---------   ---------    ---------    ---------
        Total other income and (deductions)       7,439          732        7,816       1,082        8,756         (195)

 INCOME BEFORE
    INTEREST CHARGES                             29,624       30,713       65,735      55,772      106,700      124,378

 INTEREST CHARGES:
    Interest                                      9,788       10,343       19,347      21,158       40,925       41,494
    Allowance for borrowed funds
       used during construction                     (68)        (310)         152        (381)         554         (791)
                                              ---------    ---------    ---------   ---------    ---------    ---------
    Net interest charges                          9,720       10,033       19,499      20,777       41,479       40,703

NET INCOME                                       19,904       20,680       46,236      34,995       65,221       83,675

PREFERRED STOCK DIVIDENDS                           837          917        1,830       1,885        3,778        3,765
                                              ---------    ---------    ---------   ---------    ---------    ---------

NET INCOME AFTER PREFERRED
   STOCK DIVIDENDS                            $  19,067    $  19,763    $  44,406   $  33,110    $  61,443    $  79,910
                                              =========    =========    =========   =========    =========    =========

</TABLE>

See Notes to Financial Statements.

                                       -9-

<PAGE>

<TABLE>

                     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                             STATEMENT OF CASH FLOWS
                                    UNAUDITED
                                    ---------
                             (Thousands of Dollars)




                                                           Six  Months Ended
                                                                June 30,
                                                       -------------------------
                                                           2000            1999
                                                           ----            ----
Cash Flows From Operating:
<S>                                                    <C>          <C>
   Net income                                          $  46,236    $  34,995
   Adjustments to reconcile net income to net cash
      provided by operating activities:
        Depreciation and amortization                     36,586       40,189
        Allowance for funds used during construction         152         (382)
        Deferred income taxes, net                        14,713       (7,768)
        Deferred investment tax credits, net                 755       (1,242)
        Changes in assets and liabilities:
           Receivables, net                               (9,795)     (13,547)
           Materials and supplies                          3,510       10,810
           Accounts and wages payable                     36,453       (4,561)
           Taxes accrued                                  (9,287)       5,156
           Other, net                                    (17,655)      16,135
                                                       ---------    ---------
Net cash provided by operating activities                101,668       79,785

Cash Flows From Investing:
   Construction expenditures                             (20,032)     (62,840)
   Allowance for funds used during construction             (152)         382
                                                       ---------    ---------
Net cash used in investing activities                    (20,184)     (62,458)

Cash Flows From Financing:
   Dividends on common stock                             (36,114)     (34,310)
   Dividends on preferred stock                           (1,830)      (1,697)
   Redemptions -
      Short-term debt                                       --        (46,700)
      Long-term debt                                     (82,000)     (55,000)
      Intercompany notes payable                         (12,550)        --
   Issuances -
      Long-term debt                                      51,100         --
      Intercompany notes payable                            --        127,500
                                                       ---------    ---------
Net cash used in financing activities                    (81,394)     (10,207)
                                                       ---------    ---------

Net change in cash and cash equivalents                       90        7,120
Cash and cash equivalents at beginning of year            12,536       10,180
                                                       ---------    ---------
Cash and cash equivalents at end of period             $  12,626    $  17,300
                                                       =========    =========

Cash paid during the periods:
   Interest (net of amount capitalized)                $  21,882    $  19,458
   Income taxes, net                                   $  21,712    $  21,805

</TABLE>


SUPPLEMENTAL DISCLOSURE OF NONCASH TRANSACTION:
In  the  second  quarter  of  2000,  the  Registrant  transferred  its  electric
generating  assets and  liabilities,  at historical  net book value,  to a newly
created nonregulated company,  AmerenEnergy  Generating Company, a subsidiary of
AmerenEnergy   Resources  Company,  in  exchange  for  a  promissory  note  from
Generating  Company  in the  principal  amount of $552  million  and  Generating
Company common stock. The transaction  also resulted in a deferred  intercompany
tax gain  liability  and related tax  receivable  from  AmerenEnergy  Generating
Company  in the  amount  of $219  million.  See  Note 1 in  Notes  to  Financial
Statements for further information.

See Notes to Financial Statements.

                                      -10-

<PAGE>

CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
NOTES TO FINANCIAL STATEMENTS (UNAUDITED)
June 30, 2000


Note 1 - Central Illinois Public Service Company  (AmerenCIPS or the Registrant)
is a subsidiary of Ameren Corporation  (Ameren),  which is the parent company of
the following  operating  companies:  the  Registrant,  Union  Electric  Company
(AmerenUE)  and  AmerenEnergy   Generating  Company  (Generating   Company),   a
wholly-owned  subsidiary of AmerenEnergy  Resources Company (Resources Company).
Ameren is a registered  holding company under the Public Utility Holding Company
Act of  1935  (PUHCA)  formed  in  December  1997  upon  the  merger  of  CIPSCO
Incorporated  (the Registrant's  former parent) and AmerenUE (the Merger).  Both
Ameren and its  subsidiaries  are subject to the  regulatory  provisions  of the
PUHCA.  The  operating  companies  are engaged  principally  in the  generation,
transmission,  distribution  and  sale of  electric  energy  and  the  purchase,
distribution,  transportation  and sale of natural gas in the states of Illinois
and  Missouri.  Contracts  among the  companies--dealing  with  jointly-operated
generating facilities,  interconnecting  transmission lines, and the exchange of
electric power--are regulated by the Federal Energy Regulatory Commission (FERC)
or the Securities and Exchange Commission (SEC). Administrative support services
are provided to the Registrant by a separate Ameren subsidiary,  Ameren Services
Company.  The Registrant  serves 400,000 electric and 175,000 gas customers in a
20,000 square-mile region of central and southern Illinois.

The Registrant also has a 20 percent  interest in Electric  Energy,  Inc. (EEI),
which is  accounted  for under the  equity  method of  accounting.  EEI owns and
operates an  electric  generating  and  transmission  facility in Illinois  that
supplies  electric  power  primarily to a uranium  enrichment  plant  located in
Paducah, Kentucky.

In  conjunction  with the Illinois  Electric  Service  Customer  Choice and Rate
Relief Law of 1997, on May 1, 2000,  following the receipt of all required State
and Federal  regulatory  approvals,  the  Registrant  transferred  its  electric
generating  assets and  liabilities,  at historical  net book value,  to a newly
created  nonregulated  company,  Generating Company,  for a promissory note from
Generating  Company  in the  principal  amount of $552  million  and  Generating
Company  common stock (the  Transfer).  The  promissory  note has a term of five
years  and bears  interest  at 7 percent  based on a 10-year  amortization.  The
transferred  assets  represent  a  generating  capacity of  approximately  2,900
megawatts.   Approximately  45  percent  of  the  Registrant's   employees  were
transferred to Generating Company as a part of the transaction.  The significant
components of the net assets transferred are as follows:

(Thousands of dollars)
Cash                                                      $       6,387
Material and supplies                                            53,806
Other current assets                                              5,522
Property and plant, net                                         635,031
Deferred tax assets                                              22,022
                                                         ---------------

Total assets transferred                                 $      722,768
                                                         ---------------


Accounts payable                                          $       6,541
Other current liabilities                                         3,351
Other deferred credits                                            1,804
Deferred investment tax credits                                  19,728
Deferred tax liabilities                                        139,718
                                                         ---------------

Total liabilities transferred                            $      171,142
                                                         ---------------

Net assets transferred                                   $      551,626
                                                         ---------------

Also on May 1, 2000, an electric power supply agreement was entered into between
Generating  Company and a newly  created  nonregulated  affiliate,  AmerenEnergy
Marketing  Company  (Marketing  Company),  also  a  wholly-owned  subsidiary  of
Resources Company. On the same date,  Marketing Company entered into an electric
power supply agreement with the Registrant (Power Supply Agreement) to supply it
sufficient power to meet native load requirements. A portion of the capacity and
energy supplied by Generating Company to Marketing Company will be resold to the
Registrant  for  resale to  native  load  customers  at rates  specified  by the
Illinois Commerce

                                      -11-

<PAGE>

Commission (which approximate the historical regulatory rates for generation) or
to retail  customers  allowed choice of an electric  supplier under state law at
market based prices.  This  agreement  expires  December 31, 2004. In turn,  the
Registrant  will bill these  customers at rates which  approximate the costs the
Registrant  incurs for its capacity and energy  supplied by Generating  Company.
For the two-month  period ended June 30, 2000,  $57 million of the  Registrant's
purchased power was derived under the Power Supply Agreement.

As a result of the Transfer, coupled with the Power Supply Agreement between the
Registrant  and  Marketing  Company,  prospectively  from  May 1,  2000  through
December 31, 2004, the  Registrant's  operating  revenues will include  revenues
derived from its traditional transmission and distribution  operations,  as well
as those revenues it receives from its native load  customers,  or new customers
allowed  choice of an electric  supplier  under state law.  Sales under  certain
wholesale  contracts  and  interchange  sales  will no  longer be  reflected  in
operating revenues of the Registrant.  Instead,  those revenues will be recorded
at Resources  Company.  The Registrant's  operating  expenses will include those
expenses  it  incurs  under  its  traditional   transmission   and  distribution
operations,  as well as purchased power expenses incurred under the terms of the
Power Supply Agreement.

In addition, as a result of the transaction,  the Registrant incurred a deferred
intercompany tax gain,  which resulted in an additional  deferred tax liability.
An intercompany  tax receivable with Generating  Company was established for the
deferred tax  liability.  This asset and liability will be amortized over twenty
years.  At  June  30,  2000,  the   Registrant's   deferred  tax  liability  and
intercompany tax receivable was $219 million.

Note 2 - Financial  statement note  disclosures,  normally included in financial
statements prepared in conformity with generally accepted accounting principles,
have been omitted in this Form 10-Q pursuant to the Rules and Regulations of the
SEC.  However,  in the opinion of the Registrant,  the disclosures  contained in
this Form 10-Q are adequate to make the  information  presented not  misleading.
See Notes to Financial Statements included in the 1999 Form 10-K for information
relevant to the  financial  statements  contained  in this Form 10-Q,  including
information as to the significant accounting policies of the Registrant.

Note 3 - In the  opinion of the  Registrant,  the interim  financial  statements
filed as part of this Form 10-Q  reflect  all  adjustments,  consisting  only of
normal recurring adjustments,  necessary for a fair statement of the results for
the periods presented.  The Registrant's  financial  statements were prepared to
permit the information  required in the Financial Data Schedule  (FDS),  Exhibit
27,  to be  directly  extracted  from  the  filed  statements.  The FDS  amounts
correspond  to or are  calculable  from the amounts  reported  in the  financial
statements or notes thereto.

Note 4 - Due to the  effect of  weather  on sales and  other  factors  which are
characteristic of public utility  operations,  financial results for the periods
ended June 30, 2000 and 1999, are not  necessarily  indicative of trends for any
three-month, six-month or 12-month period.

Note 5 - The Registrant has  transactions  in the normal course of business with
other Ameren  subsidiaries.  These transactions are primarily comprised of power
purchases and sales and services received or rendered.  Intercompany receivables
included in other accounts and notes receivable were  approximately  $24 million
and $12  million,  respectively,  as of June 30,  2000 and  December  31,  1999.
Intercompany   payables   included  in  accounts  and  wages   payable   totaled
approximately  $82 and  $35  million,  respectively,  as of June  30,  2000  and
December 31, 1999.

In addition,  the Registrant has the ability to borrow up to approximately  $950
million from Ameren or AmerenUE or invest funds  through a regulated  money pool
agreement.  The regulated  money pool was  established to coordinate and provide
for certain short-term cash and working capital requirements and is administered
by Ameren Services Company.  Interest is calculated at varying rates of interest
depending on the  composition  of internal and external  funds in the  regulated
money pool. At June 30, 2000, the  Registrant  had $120 million of  intercompany
borrowings  outstanding and $434 million  available  through the regulated money
pool.

Note 6 - In 1998,  the  Registrant  joined a group of companies that support the
formation of the Midwest  Independent  System  Operator  (Midwest  ISO).  An ISO
operates,  but does not own, electric  transmission systems and maintains system
reliability and security while  alleviating  certain  pricing  issues.  The FERC
conditionally  approved the  formation of the Midwest  ISO.  The  Registrant  is
evaluating  certain  issues  which are  outstanding  related to the  start-up of
operations  of the Midwest ISO,  including  the final  determination  of revenue
distribution  among  the  Midwest  ISO  members.   Further,  the  Registrant  is
evaluating  alternatives  to  membership  in the  Midwest  ISO.  At  this  time,
management  has not  decided its course of action  relative to its  transmission
business and accordingly is unable to determine the impact that operation of the
Midwest ISO or other alternatives will have on its financial condition,  results
of operations or liquidity.

                                      -12-

<PAGE>

Note 7 - Segment information for the three-month, six-month and 12-month periods
ended June 30, 2000 and 1999 is as follows:

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

(in thousands)                            Electric        Gas          Total
--------------------------------------------------------------------------------

Three months ended June 30, 2000:

Revenues                                 $169,331       $25,788       $195,119
Operating Income (Net)                     20,408         1,777         22,185
--------------------------------------------------------------------------------

Three months ended June 30, 1999:

Revenues                                 $200,336       $21,593       $221,929
Operating Income (Net)                     28,603         1,378         29,981
--------------------------------------------------------------------------------

Six months ended June 30, 2000:

Revenues                                 $371,834        $78,612      $450,446
Operating Income (Net)                     50,440          7,479        57,919
--------------------------------------------------------------------------------

Six months ended June 30, 1999:

Revenues                                 $355,576       $74,125       $429,701
Operating Income (Net)                     48,419         6,271         54,690
--------------------------------------------------------------------------------

12 months ended June 30, 2000:

Revenues                                 $811,734       $137,133      $948,867
Operating Income (Net)                     87,708         10,236        97,944
--------------------------------------------------------------------------------

12 months ended June 30, 1999:

Revenues                                 $739,050       $123,731      $862,781
Operating Income (Net)                    116,476          8,097       124,573
--------------------------------------------------------------------------------


                                      -13-

<PAGE>

                           PART II. OTHER INFORMATION


ITEM 1.  LEGAL PROCEEDINGS

     In  December  1996,  a lawsuit  was filed in the  Circuit  Court of Madison
County,  Illinois,  alleging  negligence on behalf of the  Registrant  and Dover
Elevator Company (Dover) for injuries arising out of an elevator  accident which
occurred at the  Registrant's  Newton Power Plant in November 1996, As currently
consolidated,  the case includes twenty-three named plaintiffs, all of whom were
in the employ of an independent  contractor as  boilermakers  at the time of the
incident. In January 2000, the court allowed plaintiffs to amend their claims to
include amounts for potential  punitive  damages against both the Registrant and
Dover. In April,  2000,  plaintiffs'  attorneys made their initial demand,  upon
both  defendants,  totaling  approximately  $83  million  on behalf of all named
plaintiffs.  The jury  trial of this  lawsuit is  scheduled  to begin in October
2000. At this time, the Registrant is unable to determine to what extent,  if at
all, the Registrant and/or Dover may be responsible for these claims.  While the
Registrant  cannot  predict  the  ultimate  outcome  of  this  litigation,   the
Registrant  believes it has adequate insurance to cover the ultimate claims made
against  the  Company.  At this time,  the  Registrant  believes  that the final
resolution  of this  lawsuit  will not have a  material  adverse  effect  on its
financial position, results of operation or liquidity.

     Reference  is  made  to  Note 2 -  Regulatory  Matters  (Illinois  Electric
Restructuring)  in the Notes to Financial  Statements of the  Registrant's  Form
10-K for the year  ended  December  31,  1999,  for  information  relating  to a
transmission  system rate case filed by the  Registrant  with the Federal Energy
Regulatory  Commission (FERC) in August 1999. This filing was primarily designed
to implement rates, terms and conditions for electric  transmission  service for
those retail  customers in Illinois who choose other  suppliers as allowed under
the Electric  Service  Customer  Choice and Rate Relief Law of 1997.  On May 17,
2000, the FERC issued a letter order approving a settlement of this case reached
with the FERC trial staff and other interested parties.

     Reference is made to Note 11 - Commitments and  Contingencies  in the Notes
to  Financial  Statements  of the  Registrant's  Form  10-K for the  year  ended
December 31, 1999 for information  regarding unfair labor practice charges filed
with the National Labor  Relations  Board (NLRB) by the  International  Union of
Operating  Engineers Local 148 and the  International  Brotherhood of Electrical
Workers  Local 702  relating  to the  lockout by the  Registrant  of both unions
during  1993.  On May 9, 2000,  the U.S.  Court of Appeals  for the  District of
Columbia Circuit issued a ruling upholding the NLRB's August 1998 decision which
ruled in favor of the  Registrant  and held that the  lockout  was  lawful.  The
unions are seeking review of the court's decision by the U.S. Supreme Court.

     Reference  is made to  "Regulation"  section  in  Item 1.  Business  of the
Registrant's  Form 10-K for the year ended  December 31, 1999,  for  information
relating to litigation  concerning the alleged exposure to carcinogens contained
in coal tar at the  Registrant's  Taylorville  gas plant site. On June 23, 2000,
the  Registrant  filed an appeal  with the  Illinois  Supreme  Court to review a
decision  issued by the  Illinois  Appellate  Court in March 2000 which upheld a
$3.2 million  verdict in favor of the plaintiffs.  The Registrant  believes that
final  disposition of this matter will not have a material adverse effect on its
financial position, results of operation or liquidity.

     Reference  is  made  to  Item  1.  Legal  Proceedings  in  Part  II of  the
Registrant's  Form 10-Q for the  quarterly  period  ended  March 31,  2000,  for
information relating to the National Ambient Air Quality Standards for ozone and
particulate matter litigation.  On May 22, 2000, the United States Supreme Court
granted  certiorari  and agreed to review the United States Court of Appeals for
the  District of Columbia  Circuit's  decision to remand the ambient air quality
standard  regulations to the United States  Environmental  Protection Agency for
reconsideration.  At this time, the Registrant is unable to predict the ultimate
impact of those revised air quality standards on its future financial condition,
results of operation or liquidity.


ITEM 5.  OTHER INFORMATION

     Any stockholder  proposal  intended for inclusion in the proxy material for
the  Registrant's  2001 annual meeting of  stockholders  must be received by the
Registrant by November 30, 2000.

                                      -14-

<PAGE>

     In addition,  under the  Registrant's  By-Laws,  stockholders who intend to
submit a proposal  in person at an annual  meeting,  or who intend to nominate a
director at a meeting,  must  provide  advance  written  notice along with other
prescribed  information.  In  general,  such  notice  must  be  received  by the
Secretary of the  Registrant not later than 60 nor earlier than 90 days prior to
the  first  anniversary  of  the  preceding  year's  annual  meeting.   For  the
Registrant's  2001  annual  meeting  of  stockholders,  written  notice  of  any
in-person stockholder proposal or director nomination must be received not later
than February 24, 2001 or earlier than January 25, 2001.


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

          (a)  Exhibits.

               Exhibit 10 - Asset Transfer  Agreement  between Central  Illinois
               Public Service Company and AmerenEnergy  Generating Company dated
               as of May 1, 2000.

               Exhibit 12 -  Computation  of Ratio of Earnings to Fixed  Charges
               and Preferred  Stock Dividend  Requirement,  12 Months Ended June
               30, 2000.

               Exhibit 27 - Financial Data Schedule.

          (b)  Reports on Form 8-K.  The  Registrant  filed a report on Form 8-K
               dated  May  5,  2000  reporting  the  transfer  of  its  electric
               generating   facilities   to  a  new   nonregulated   subsidiary,
               AmerenEnergy Generating Company.



                                   SIGNATURES

     Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned thereunto duly authorized.

                                          CENTRAL ILLINOIS PUBLIC
                                              SERVICE COMPANY
                                               (Registrant)


                                        By   /S/ Warner L. Baxter
                                           ------------------------
                                                 Warner L. Baxter
                                          Vice President and Controller
                                          (Principal Accounting Officer)


Date:  August 14, 2000

                                      -15-