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 EXCHANGE ACT OF 1934

         For Quarterly Period Ended September 30, 2001

[  ]     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
     November 13, 2001: 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

            Item 1.  Financial Statements (Unaudited)

                Balance Sheet
                - September 30, 2001 and December 31, 2000                10

                Statement of Income
                - Three months, nine months and 12 months ended
                September 30, 2001 and 2000                               11

                Statement of Cash Flows
                - Nine months ended September 30, 2001 and 2000           12

                Notes to Financial Statements                             13

            Item 2. Management's Discussion and Analysis of
            Financial Condition and Results of Operations                  2

            Item 3.  Quantitative and Qualitative Disclosures
            About Market Risk                                              8


Part II     Other Information

            Item 5.  Other Information                                    17

            Item 6.  Exhibits and Reports on Form 8-K                     17






<PAGE>

                         PART I - FINANCIAL INFORMATION

ITEM 1.  FINANCIAL STATEMENTS (UNAUDITED).

The unaudited  financial  statements of Central  Illinois Public Service Company
(AmerenCIPS or the Registrant) appear on pages 10 through 16 of this report.

ITEM 2. MANAGEMENT'S  DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
OF OPERATIONS.

OVERVIEW

The Registrant is a subsidiary of Ameren Corporation (Ameren), a holding company
registered  under the Public Utility Holding  Company Act of 1935 (PUHCA).  Both
Ameren and its subsidiaries  are subject to the regulatory  provisions of PUHCA.
The Registrant is a public utility operating company engaged  principally in the
transmission,  distribution  and  sale of  electric  energy  and  the  purchase,
distribution,  transportation  and sale of natural gas in the state of Illinois.
The  Registrant  serves  325,000  electric and 175,000 gas customers in a 20,000
square-mile region of central and southern Illinois.

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),  which is a wholly owned
subsidiary  of  Ameren  (the  Transfer).   Discussion  below  under  Results  of
Operations  reflects  that as a result of the  Transfer,  from May 1, 2000,  the
Registrant's  operating  revenues  will only include  revenues  derived from its
traditional  transmission  and  distribution  operations,  and 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 only include those expenses it incurs under
its traditional  transmission  and  distribution  operations,  and for purchased
power under an electric power supply  agreement with Resources  Company's  newly
created marketing subsidiary, AmerenEnergy Marketing Company (Marketing Company)
(the Power Supply  Agreement).  The Registrant also has a 20 percent interest in
Electric Energy,  Inc. (EEI). EEI owns and/or operates  electric  generating and
transmission  facilities in Illinois that supply  electric power  primarily to a
uranium enrichment plant located in Paducah,  Kentucky. The Registrant continues
to buy 20% of the  excess  generating  output  of EEI and sells  this  output as
interchange sales.

The Registrant's  financial  statements include charges for services that Ameren
Services  Company  (Ameren  Services),  a  wholly  owned  subsidiary  of  Ameren
Corporation, provides to the Registrant. Ameren Services provides shared support
services  for all Ameren  subsidiaries.  Charges are based upon the actual costs
incurred by Ameren Services, as required by PUHCA.

The following  discussion and analysis  should be read in  conjunction  with the
Notes  to  Financial  Statements  beginning  on page  12,  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 2000 Form 10-K.

RESULTS OF OPERATIONS

Earnings
Third  quarter  2001  earnings of $24 million  decreased  $6 million from 2000's
third quarter  earnings.  Earnings for the nine months ended  September 30, 2001
decreased $32 million from the year-ago period to $43 million.  Earnings for the
12 months ended September 30, 2001 were $44 million,  a $6 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, expenses relating to the
withdrawal from the electric  transmission  related Midwest  Independent  System
Operator (Midwest ISO), charges for coal contract termination payments,  changes
in interest expense, and changes in income and property taxes.



                                       2

<PAGE>
The  significant  items  affecting  revenues,  costs  and  earnings  during  the
three-month,  nine-month and 12-month  periods ended September 30, 2001 and 2000
are detailed below.
<TABLE>
<CAPTION>
<S>                                            <C>                       <C>                      <C>
Electric Operations

Electric Operating Revenues                Variations for periods ended September 30, 2001
                                               from comparable prior-year periods
-----------------------------------------------------------------------------------------------------------------------
(Millions of Dollars)                            Three Months              Nine Months              Twelve Months
                                                 ------------              -----------              -------------
-----------------------------------------------------------------------------------------------------------------------

Credits to customers                             $    --                  $  --                     $ (8)
Effect of abnormal weather                             6                     15                       21
Growth and other                                       9                     (6)                     (12)
Interchange sales                                     (2)                   (49)                     (72)
-----------------------------------------------------------------------------------------------------------------------
                                                 $    13                  $ (40)                    $(71)
-----------------------------------------------------------------------------------------------------------------------
</TABLE>

Electric  revenues for the three months ended September 30, 2001,  increased $13
million  compared to the prior three- month period  primarily due to an increase
in retail sales  partially  offset by a decrease in interchange  sales which are
now  being  recorded  at  Resources  Company  as a result  of the  Transfer.  In
addition,  sales under certain wholesale  contracts are no longer being included
in the Registrant's operating revenues as a result of the Transfer.

Electric  revenues for the nine months ended  September 30, 2001,  decreased $40
million compared to the prior  nine-month  period primarily due to a decrease in
interchange sales, which are now being recorded at Resources Company as a result
of the Transfer.  In addition,  sales under certain  wholesale  contracts are no
longer being included in the Registrant's  operating revenues as a result of the
Transfer. The decreases in interchange and wholesale sales were partially offset
by increases in residential  and  commercial  sales of 3 percent and 10 percent,
respectively,  primarily  due to warmer  weather,  and an increase in industrial
sales of 49  percent  due to a new  industrial  customer  contract  that  became
effective in August 2000.

Electric  revenues  for the 12 months ended  September  30, 2001  decreased  $71
million,  compared to the same prior year period,  primarily due to decreases in
interchange sales as a result of the Transfer. In addition,  sales under certain
wholesale  contracts are no longer being included in the Registrant's  operating
revenues as a result of the  Transfer.  Decreases in  interchange  and wholesale
sales were partially  offset by increases in  weather-sensitive  residential and
commercial sales of 7 percent and 11 percent,  respectively,  and an increase in
industrial  sales of 52 percent due to a new industrial  customer  contract that
became effective in August 2000.

<TABLE>
<CAPTION>
<S>                                          <C>                     <C>                       <C>
Fuel and Purchased Power               Variations for periods ended September 30, 2001
                                              from comparable prior-year periods
----------------------------------------------------------------------------------------------------------------------
(Millions of Dollars)                           Three Months            Nine Months              Twelve Months
                                                ------------            -----------              -------------
----------------------------------------------------------------------------------------------------------------------
Fuel:
    Generation                                    $    -                  $ (57)                   $ (97)
    Price                                              -                      -                        1
    Generation efficiencies and other                 11                     10                       10
    Coal contract termination payments                 -                      -                      (52)
Purchased power                                        8                    115                      202
---------------------------------------------------------------------------------------------------------------------
                                                   $  19                  $  68                    $  64
---------------------------------------------------------------------------------------------------------------------
</TABLE>

Fuel and purchased power costs for the three and nine months ended September 30,
2001 increased $19 million and $68 million, respectively,  compared to the prior
year  periods,  primarily  as  a  result  of  increased  purchased  power  under
provisions  of  the  Power  Supply  Agreement,  partially  offset  by  decreased
generation resulting from the Transfer.

The $64  million  increase in fuel and  purchased  power costs for the 12 months
ended  September  30, 2001 compared to the  prior-year  period was primarily the
result of increased  purchased  power under the  provisions  of the Power Supply
Agreement, partially offset by decreased generation resulting from the Transfer.

Gas Operations
Gas revenues for the three-months ended September 30, 2001, decreased $3 million
compared to the same period in the prior year  primarily  due to lower gas costs
recovered  through the purchased  gas  adjustment  clause.  Gas revenues for the
nine-month and 12-month  periods ended  September 30, 2001 increased $30 million
and $66 million,  respectively,  compared to the same year-ago periods primarily
due higher gas costs recovered through the Registrant's purchased gas adjustment
clause, partially offset by lower retail sales.

                                        3
<PAGE>

Gas costs for the nine month and  12-month  periods  ended  September  30, 2001,
increased  $34 million and $67 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  expenses  consist  primarily  of  wages,   employee  benefits,
professional  services and expenses associated with support services provided by
Ameren Services.  Other operating expense variations reflected recurring factors
such as growth, inflation, labor and employee benefit costs and the Transfer.

Other  operations  expenses  increased  $6 million  for the three  months  ended
September  30,  2001  compared  to the same  year-ago  period  primarily  due to
increases  in  employee  benefits  costs  resulting  from  changes in  actuarial
assumptions  as well as a decrease in prior year expenses  related to a coal tar
environmental  remediation.  Other operations  expenses decreased $8 million for
the nine months ended  September 30, 2001,  compared to the same year-ago period
primarily due to lower labor costs resulting from the Transfer, partially offset
by an increase in employee  benefits  costs  resulting from changes in actuarial
assumptions and investment  performance of employee benefit plans' assets. Other
operations  expenses decreased $22 million for the 12 months ended September 30,
2001,  compared to the same year-ago period,  primarily due to lower labor costs
resulting  from the  Transfer,  partially  offset by the  charge  in the  fourth
quarter of 2000 for withdrawal from the Midwest ISO (see discussion  below under
"Electric Industry  Restructuring" for further  information) and the increase in
employee benefits costs noted above.

Support services provided by Ameren Services are based on actual costs incurred.
For each of the three months ended September 30, 2001 and 2000,  other operating
expenses  provided by Ameren  Services  totaled  $13  million  and $10  million,
respectively.  For each of the nine months  ended  September  30, 2001 and 2000,
support services  provided by Ameren Services  totaled $41 million.  For each of
the 12 months ended September 30, 2001 and 2000,  support  services  provided by
Ameren Services totaled $51 million and $57 million, respectively.

Maintenance  expenses  for the  three  months  ended  September  30,  2001  were
comparable to the three months ended  September 30, 2000.  Maintenance  expenses
for the nine months and 12 months ended September 30, 2001 decreased $14 million
and $42 million,  respectively,  from the comparable  year-ago periods primarily
due to decreased power plant maintenance resulting from the Transfer.

Depreciation and amortization  expenses for the three months ended September 30,
2001 were comparable to the three months ended September 30, 2000.  Depreciation
and  amortization  expenses  decreased  $12 million and $21 million for the nine
months and 12 months ended  September  30, 2001,  respectively,  compared to the
same year-ago periods due to the decreased  depreciable  property resulting from
the Transfer.

Taxes
Income taxes for the three months, nine months and 12 months ended September 30,
2001, decreased $7 million, $21 million and $12 million, respectively, primarily
due to lower pretax income.

Other taxes for the three months ended September 30, 2001 were comparable to the
three months ended  September  30, 2000.  Other taxes for the nine months and 12
months ended  September 30, 2001 decreased $11 million in each period  primarily
due to lower property taxes and payroll taxes as a result of the Transfer.

Other Income and Deductions
For the three,  nine and 12 months ended September 30, 2001,  miscellaneous  net
increased $1 million, $13 million and $23 million, respectively, compared to the
same  year-ago  periods,   primarily  due  to  interest  income  earned  on  the
subordinated  promissory note receivable from Generating  Company as part of the
Transfer.  See  "Electric  Industry  Restructuring"  and  Note 1 under  Notes to
Financial Statements for further discussion of the promissory note.

Balance Sheet
The $27 million decrease in trade accounts receivable was due primarily to lower
gas  revenues in August and  September  2001,  compared to November and December
2000.


                                       4
<PAGE>

The $40 million  reduction in intercompany  notes  receivable is the result of a
payment  received  from  Generating  Company as part of the debt  service on the
subordinated  promissory note. See "Electric Industry  Restructuring"  below for
further discussion.

The $13 million  increase in fossil fuel is primarily due to lower gas inventory
in November and December  2000  resulting  from  increased gas usage due to cold
weather and an increase in gas inventory in September  2001 in  preparation  for
the winter season.

Changes in taxes accrued,  and other accounts and notes receivable resulted from
the  timing  of  various  payments  to  taxing  authorities  and  receipts  from
customers.  The $194 million reduction in intercompany  notes payable was due to
the repayment of funds borrowed from the regulated  money pool (see Note 2 under
Notes to Financial Statements for further discussion) and the repayment of funds
owed to Generating Company as a result of the Transfer.

LIQUIDITY AND CAPITAL RESOURCES

Cash  provided by operating  activities  totaled $81 million for the nine months
ended September 30, 2001, compared to $139 million during the same 2000 period.

Cash flows  provided  by  investing  activities  totaled $6 million for the nine
months  ended  September  30, 2001 and cash flows used in  investing  activities
totaled $31 million for the nine months ended  September 30, 2000.  Construction
expenditures  for the nine months ended September 30, 2001, for constructing new
or improving existing  facilities,  were $34 million.  The $40 million change in
intercompany  notes  receivable  represents  payment  received  from  Generating
Company as part of the debt  service on the  subordinated  promissory  note (see
"Electric Industry Restructuring" below for further discussion).

Cash flows used in financing  activities totaled $92 million for the nine months
ended September 30, 2001,  compared to $100 million during the same 2000 period.
The Registrant's principal financing activities for the nine months included the
issuance  of  long-term  debt and the  payment of  intercompany  notes  payable,
partially offset by the redemption 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 (SEC) 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 September
30, 2001,  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 September 30, 2001,
the Registrant had no outstanding short-term borrowings.

Also, the Registrant has the ability to borrow up to approximately  $899 million
from Ameren or from two of Ameren's other  subsidiaries,  Union Electric Company
(AmerenUE) and Ameren  Services,  through a regulated money pool agreement.  The
total amount  available to the  Registrant  at any given time from the regulated
money  pool is  reduced  by the  amount  of  borrowings  by  AmerenUE  or Ameren
Services,  but increased to the extent  AmerenUE or Ameren Services have surplus
funds and the availability of other external  borrowing  sources.  The regulated
money pool was established to coordinate and provide for certain short-term cash
and working capital requirements of the Registrant, AmerenUE and Ameren Services
and is administered by Ameren Services.  Interest is calculated at varying rates
of interest  depending on the  composition of internal and external funds in the
regulated  money pool. For the three months and nine months ended  September 30,
2001,  the average  interest rate for the regulated  money pool was 3.67 percent
and 4.51 percent,  respectively.  At September 30, 2001,  the Registrant had $29
million  of  intercompany  borrowings  outstanding  and $399  million  available
through the regulated money pool subject to reduction for borrowings by AmerenUE
or Ameren Services.

In April 2001, the Registrant filed with the SEC a shelf registration  statement
on Form S-3 authorizing the offering from time to time of senior notes in one or
more series with an offering price not to exceed $250 million.  The SEC declared
the registration  statement  effective in May 2001. In June 2001, the Registrant
issued $150 million of the senior notes with an interest  rate of 6.625  percent
due June 2011. The proceeds of these senior notes were used to repay  short-term
debt borrowed  through the regulated  money pool and first  mortgage bonds which
matured in June 2001.


                                       5
<PAGE>
During the course of Ameren's resource planning,  several alternatives are being
considered to satisfy  anticipated  regulatory  load  requirements  for 2001 and
beyond for the Registrant, AmerenUE and Resources Company. AmerenUE purchased 50
megawatts  of  capacity  and  energy  during  the third  quarter  of 2001 and is
considering  proposals  for  purchases  of up to 500  megawatts  of capacity and
energy,  for the summer of 2002 and beyond,  among other  things.  At this time,
management is unable to predict which course of action it will pursue to satisfy
these  requirements  and their  ultimate  impact on the  Registrant's  financial
position, results of operations or liquidity.

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,  over the past two years,  the Registrant has reached
agreements  with all of the its major  collective  bargaining  units  which will
permit the Registrant to manage its labor costs and practices effectively in the
future. The Registrant 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 to what extent
these alternatives to reduce its overall cost structure will be executed nor can
it  determine  the impact of these  actions on its  future  financial  position,
results of operations or liquidity.

ELECTRIC INDUSTRY RESTRUCTURING

Certain states are considering  proposals or have adopted  legislation that will
promote  competition  at the  retail  level.  During  2000  and in  early  2001,
deregulation  laws  established  in the state of  California,  coupled with high
energy prices, increasing demands for power by users in that state, transmission
constraints,  and limited generation resources,  among other things,  negatively
impacted  several  major  electric  utilities  in that state.  Federal and state
regulators and legislators  have proposed and  implemented,  in part,  different
courses of action to attempt to address these issues.  The  Registrant  does not
maintain  utility  operations  in the state of  California,  nor does it provide
energy  directly to utilities in that state.  At this time,  the  Registrant  is
uncertain what impact,  if any, changes in deregulation laws will have on future
federal  and  state   deregulation   laws,   which  could  directly  impact  the
Registrant's future financial position, results of operations or liquidity.

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 is 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 remaining  commercial and industrial customers were offered choice on
December 31, 2000.  Commercial and industrial customers represent  approximately
45 percent of the Registrant's total sales. As of September 30, 2001, the impact
of retail  direct access on the  Registrant's  financial  condition,  results of
operations and liquidity was immaterial. Retail direct access will be offered 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 Generating Company in exchange for a subordinated promissory note
from Generating  Company in the principal amount of $552 million (the Transfer).
The  promissory  note has a term of five years and bears  interest  at 7 percent
based  on  a  10-year  amortization.   Debt  service  during  the  term  of  the
subordinated promissory note is payable solely from "available cash," defined as
cash available after payment of all operating and maintenance  expenses,  senior
debt service,  capital  expenditures,  taxes and reasonable reserves for working
capital and other corporate  purposes as determined by Generating Company in its
discretion.  Any installment payment amount that is not paid when due because of
the  available  cash  limitation  will be payable  when  available  cash becomes
sufficient  to permit the  payment,  or else carried  forward to  maturity.  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.

In conjunction with the Transfer, an electric power supply agreement was entered
into between  Generating  Company and a newly  created  nonregulated  affiliate,
Marketing  Company,  also a wholly owned  subsidiary  of Resources  Company.  In
addition,  Marketing  Company  entered into the Power Supply  Agreement with the
Registrant to supply it sufficient  energy and capacity to meet its  obligations
as a public  utility  through  December  31, 2004. A portion of the capacity and

                                       6
<PAGE>

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 (ICC) (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.  In turn,  the Registrant  will
bill these customers at rates which  approximate the costs the Registrant incurs
for its capacity and energy supplied by Marketing Company.  For the three-month,
nine-month and 12-month  periods ended  September 30, 2001,  $117 million,  $318
million and $418 million,  respectively, of the Registrant's power was purchased
through 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 September  30, 2001,  the  Registrant's  deferred tax  liability  and
intercompany tax receivable was $199 million.

Midwest ISO and Alliance RTO
In the  fourth  quarter of 2000,  the  Registrant  announced  its  intention  to
withdraw  from the Midwest ISO and to join the  Alliance  Regional  Transmission
Organization  (Alliance  RTO),  and  recorded a pretax  charge to earnings of $8
million ($5 million after taxes),  which related to the  Registrant's  estimated
obligation  under the Midwest ISO  agreement  for costs  incurred by the Midwest
ISO, plus  estimated  exit costs.  During first quarter 2001, the Federal Energy
Regulatory Commission (FERC) conditionally approved the formation, including the
rate  structure,  of the Alliance RTO, and the Registrant  announced that it had
signed an agreement to join the Alliance RTO. Also in the first quarter 2001, in
a  proceeding  before the FERC,  the Alliance RTO and the Midwest ISO reached an
agreement  that would enable the Registrant to withdraw from the Midwest ISO and
to join the  Alliance  RTO.  In the  second  quarter  of 2001,  this  settlement
agreement was approved by the FERC.  Additional regulatory approvals of the SEC,
FERC  and  the ICC may be  required  in  connection  with  various  transactions
involving the Alliance RTO relating to its organization,  capitalization and the
possible transfer of transmission assets. Such approvals,  if required,  will be
sought at the appropriate  times. The Alliance RTO is expected to be operational
within 90-120 days after the FERC's  approval.  At this time,  the Registrant is
unable to determine the impact that its withdrawal  from the Midwest ISO and its
participation in the Alliance RTO will have on its future  financial  condition,
results of operations or liquidity.

ACCOUNTING MATTERS

In July 2001, the FASB issued SFAS No. 141, "Business  Combinations,"  SFAS 142,
"Goodwill  and Other  Intangible  Assets," and SFAS 143,  "Accounting  for Asset
Retirement Obligations." SFAS 141 requires business combinations to be accounted
for under the purchase  method of  accounting,  which  requires one party in the
transaction  to be identified as the acquiring  enterprise and for that party to
record the assets and  liabilities  of the  acquired  enterprise  at fair market
value rather than historical cost. It prohibits use of the  pooling-of-interests
method of accounting  for business  combinations.  SFAS 141 is effective for all
business combinations  initiated after June 30, 2001, or transactions  completed
using the  purchase  method  after June 30,  2001.  SFAS 142  requires  goodwill
recorded  in the  financial  statements  to be tested  for  impairment  at least
annually,  rather than amortized  over a fixed period,  with  impairment  losses
recorded in the income  statement.  SFAS 142 is  effective  for all fiscal years
beginning  after  December  15,  2001.  SFAS 143  requires an entity to record a
liability  and  corresponding  asset  representing  the  present  value of legal
obligations associated with the retirement of tangible,  long-lived assets. SFAS
143 is effective for fiscal years  beginning  after June 15, 2002.  SFAS 141 and
SFAS  142 are  not  expected  to  have a  material  effect  on the  Registrant's
financial  position,  results of operations or liquidity upon adoption.  At this
time,  the  Registrant  is  assessing  the  impact of SFAS 143 on its  financial
position, results of operations or liquidity upon adoption.


                                       7
<PAGE>
ITEM 3.  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK.

Market  risk  represents  the risk of changes in value of a physical  asset or 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  the  Registrant's,   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 and the Registrant also
face  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.

Ameren's risk management objective is to optimize its physical generating assets
within  prudent  risk  parameters.  Risk  management  policies are set by a Risk
Management  Steering  Committee,  which  is  comprised  of  senior-level  Ameren
officers.

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 and
fixed-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 2002 as compared to 2001, the
Registrant's interest expense would increase by approximately $2 million 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-rate  preferred stock, as of September 30,
2001, continued to be outstanding throughout 2002, and that the average interest
rates for these  instruments  increased  one  percentage  point over  2001.  The
estimate does not consider the effects of the reduced level of potential 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
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.

Since  the  Registrant  does not  have a  provision  similar  to the PGA for its
electric  operations,  purchased power commodity 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"  above for
further discussion).

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 and
financial  performance.  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,  2000,  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,  including changes in regulatory policy; 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;  the  effects of
withdrawal  from the Midwest ISO and  membership  in the  Alliance  RTO;  future
market prices for purchased  power,  electricity and natural gas,  including the

                                       8
<PAGE>

use of financial  instruments;  average  rates for  electricity  in the Midwest;
business and economic  conditions;  the impact of the adoption of new accounting
standards; interest rates; weather conditions; fuel availability;  the impact of
current  environmental  regulations on utilities;  monetary and fiscal policies;
future  wages  and  employee  benefits  costs;  and  legal  and   administrative
proceedings.

                                       9
<PAGE>
<TABLE>
<CAPTION>

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


<S>                                           <C>             <C>
                                                September 30,   December 31,
ASSETS                                              2001           2000
------                                          -------------   ------------
Property and plant, at original cost:
   Electric                                        $1,208,590   $1,195,418
   Gas                                                281,933      273,573
                                                   ----------   ----------
                                                    1,490,523    1,468,991
   Less accumulated depreciation and amortization     683,632      654,897
                                                   ----------   ----------

                                                      806,891      814,094
Construction work in progress                          10,759        6,558
                                                   ----------   ----------
         Total property and plant, net                817,650      820,652
                                                   ----------   ----------
Investments and other assets:
   Intercompany notes receivable                      468,981      511,701
   Intercompany tax receivable                        184,004      194,975
   Other assets                                        17,996       17,085
                                                   ----------   ----------
         Total investments and other assets           670,981      723,761
                                                   ----------   ----------
Current assets:
   Cash and cash equivalents                           25,393       29,801
   Accounts receivable - trade (less allowance
         for doubtful accounts of $1,470 and          133,509      160,996
         $1,777, respectively)
   Other accounts and notes receivable                 41,166       25,035
   Intercompany notes receivable                       42,720       39,925
   Intercompany tax receivable                         14,927       15,809

   Materials and supplies, at average cost -
      Fossil fuel                                      36,049       22,560
      Other                                            10,256        9,821
   Other                                                5,707        6,240
                                                   ----------   ----------
         Total current assets                         309,727      310,187
                                                   ----------   ----------
   Regulatory assets                                   15,328       12,541
                                                   ----------   ----------
Total Assets                                       $1,813,686   $1,867,141
                                                   ==========   ==========

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                                  445,453      435,211
                                                   ----------   ----------
         Total common stockholder's equity            565,486      555,244
   Preferred stock not subject to mandatory            80,000       80,000
         redemption
   Long-term debt                                     579,015      463,174
                                                   ----------   ----------
        Total capitalization                        1,224,501    1,098,418
                                                   ----------   ----------
Current liabilities:
   Current maturity of long-term debt                  33,000       30,000
   Intercompany notes payable                          29,255      223,320
   Accounts and wages payable                         106,973      106,739
   Accumulated deferred income taxes                   19,657       19,639
   Taxes accrued                                       36,164       13,899
   Other                                               35,886       33,448
                                                   ----------   ----------
         Total current liabilities                    260,935      427,045
                                                   ----------   ----------
Accumulated deferred income taxes                     258,452      273,505
Accumulated deferred investment tax credits            12,170       12,965
Regulatory liability                                   35,341       34,898
Other deferred credits and liabilities                 22,287       20,310
                                                   ----------   ----------
Total Capital and Liabilities                      $1,813,686   $1,867,141
                                                   ==========   ==========
</TABLE>

See Notes to Financial Statements.

                                        10
<PAGE>
<TABLE>
<CAPTION>

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


                                                Three Months Ended       Nine Months Ended      Twelve Months Ended
                                                  September 30,             September 30,          September 30,
                                                ------------------       -----------------      -------------------
                                                 2001         2000         2001        2000        2001         2000
                                                 ----         ----         ----        ----        ----         ----
<S>                                         <C>          <C>         <C>          <C>         <C>          <C>

 OPERATING REVENUES:
    Electric                                  $ 210,353    $ 197,405   $ 529,455    $ 569,239   $ 677,343    $ 748,736
    Gas                                          18,808       21,843     130,603      100,455     206,919      141,102
    Other                                           106         --           300         --           300         --
                                              ---------    ---------   ---------    ---------   ---------    ---------
 Total operating revenues                       229,267      219,248     660,358      669,694     884,562      889,838

 OPERATING EXPENSES:
    Operations
       Fuel and purchased power                 123,354      104,560     336,019      268,318     438,135      374,222
       Gas                                        9,283       10,081      88,221       54,241     144,315       77,267
       Other                                     32,551       26,505      90,304       97,951     125,910      147,650
                                              ---------    ----------  ---------    ---------   ---------    ----------
                                                165,188      141,146     514,544      420,510     708,360      599,139
    Maintenance                                   7,767        7,494      21,096       35,547      30,012       71,820
    Depreciation and amortization                12,310       12,221      36,440       48,807      48,717       70,084
    Income taxes                                 13,967       21,044      26,047       47,165      22,462       34,558
    Other taxes                                   6,057        6,349      17,934       28,752      27,814       39,144
                                              ---------    ---------   ---------    ---------   ---------    ---------
       Total operating expenses                 205,289      188,254     616,061      580,781     837,365      814,745

 OPERATING INCOME                                23,978       30,994      44,297       88,913      47,197       75,093

 OTHER INCOME AND (DEDUCTIONS):
    Miscellaneous, net                           11,119       10,172      31,011       17,988      40,903       18,404
                                              ---------    ---------   ---------    ---------   ---------    ---------
        Total other income and (deductions)      11,119       10,172      31,011       17,988      40,903       18,404

 INCOME BEFORE
    INTEREST CHARGES                             35,097       41,166      75,308      106,901      88,100       93,497

 INTEREST CHARGES:
    Interest                                      9,889        9,391      29,418       28,738      41,249       39,568
    Allowance for borrowed funds used
       during construction                          (47)         (53)       (179)          99        (516)         163
                                              ---------    ---------   ---------    ---------   ----------   ---------
    Net interest charges                          9,842        9,338      29,239       28,837      40,733       39,731

NET INCOME                                       25,255       31,828      46,069       78,064      47,367       53,766

PREFERRED STOCK DIVIDENDS                           902        1,027       2,778        2,857       3,803        3,848
                                              ---------    ---------   ---------    ---------   ---------    ---------

NET INCOME AFTER PREFERRED
   STOCK DIVIDENDS                            $  24,353    $  30,801   $  43,291    $  75,207   $  43,564    $  49,918
                                              =========    =========   =========    =========   =========    =========
</TABLE>

Notes to Financial Statements.

                                       11
<PAGE>

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


                                                          Nine Months Ended
                                                            September 30,
                                                         -------------------
                                                           2001         2000
                                                           ----         ----
Cash Flows From Operating:
   Net income                                          $  46,069    $  78,064
   Adjustments to reconcile net income to net cash
      provided by operating activities:
        Depreciation and amortization                     36,440       48,807
        Allowance for funds used during construction        (179)          99
        Deferred income taxes, net                       (14,532)       9,503
        Deferred investment tax credits, net                (795)         607
        Changes in assets and liabilities:
           Receivables, net                               11,356      (25,423)
           Materials and supplies                        (13,924)      (7,617)
           Accounts and wages payable                    (17,866)      84,403
           Taxes accrued                                  22,265       (1,465)
           Other, net                                     12,395      (47,711)
                                                       ---------    ---------
Net cash provided by operating activities                 81,229      139,267

Cash Flows From Investing:
   Construction
expenditures                                             (34,098)     (30,602)
   Allowance for funds used during construction              179          (99)
   Intercompany notes receivable                          39,925         --
                                                       ---------    ---------
Net cash provided by (used in) investing activities        6,006      (30,701)

Cash Flows From Financing:
   Dividends on common stock                             (14,800)     (54,171)
   Dividends on preferred stock                           (2,778)      (2,857)
   Redemptions -
      Long-term debt                                     (30,000)     (87,000)
      Intercompany notes payable                        (194,065)      (7,180)
   Issuances -
      Long-term debt                                     150,000       51,100
                                                       ---------    ---------
Net cash used in financing activities                    (91,643)    (100,108)
                                                       ---------    ---------

Net change in cash and cash equivalents                   (4,408)       8,458
Cash and cash equivalents at beginning of year            29,801       12,536
                                                       ---------    ---------
Cash and cash equivalents at end of period             $  25,393    $  20,994
                                                       =========    =========

Cash paid during the periods:
   Interest (net of amount capitalized)                $  25,372    $  30,619
   Income taxes, net                                   $  16,531    $  34,509




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.

                                       12

<PAGE>



CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
NOTES TO FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2001


Note 1 - Summary of Significant Accounting Policies

Basis of Presentation
Central  Illinois  Public Service  Company  (AmerenCIPS or the  Registrant) is a
subsidiary of Ameren  Corporation  (Ameren),  a holding company under the Public
Utility Holding Company Act of 1935 (PUHCA). Ameren is the parent company of the
following  operating  subsidiaries:   the  Registrant,  Union  Electric  Company
(AmerenUE),  and AmerenEnergy  Generating Company (Generating Company), a wholly
owned subsidiary of AmerenEnergy  Resources Company  (Resources  Company).  Both
Ameren and its subsidiaries  are subject to the regulatory  provisions of PUHCA.
The Registrant is a public  utility  engaged  principally  in the  transmission,
distribution  and  sale  of  electric  energy  and the  purchase,  distribution,
transportation and sale of natural gas in the state of Illinois. Contracts among
the  Registrant  and other  Ameren  subsidiaries--dealing  with  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 (Ameren Services). The
Registrant  serves  325,000  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/or operates  electric  generating
and transmission  facilities in Illinois that supply electric power primarily to
a  uranium  enrichment  plant  located  in  Paducah,  Kentucky.  The  Registrant
continues  to buy 20% of the  excess  generating  output of EEI and  sells  this
output as interchange sales.

In  conjunction  with the Illinois  Electric  Service  Customer  Choice and Rate
Relief  Law of 1997 (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
Generating  Company in exchange for a promissory note from Generating Company in
the principal  amount of $552 million (the Transfer).  The promissory note bears
interest  at 7 percent and has a term of five years  payable  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.

In conjunction with the Transfer, an electric power supply agreement was entered
into between  Generating Company and its newly created  nonregulated  affiliate,
AmerenEnergy  Marketing  Company  (Marketing  Company),   also  a  wholly  owned
subsidiary of Resources Company. In addition,  Marketing Company entered into an
electric  power supply  agreement  with the  Registrant  to supply it sufficient
energy and capacity to meet its obligations as a public utility through December
31, 2004 (the Power  Supply  Agreement).  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 (ICC) (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.  In turn,  the Registrant  will
bill these customers at rates which  approximate the costs the Registrant incurs
for its capacity and energy supplied by Marketing Company.  For the three-month,
nine-month and 12-month  periods ended  September 30, 2001,  $117 million,  $318
million and $418 million,  respectively, 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.

                                       13

<PAGE>


Interim Financial Statements
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 2000 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.

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.

Factors Affecting Business
Due to the effect of weather on sales and other factors which are characteristic
of public utility operations,  financial results for the periods ended September
30, 2001 and 2000, are not necessarily indicative of trends for any three-month,
nine-month or 12-month period.

Reclassifications
Certain reclassifications have been made to prior years' financial statements to
conform with 2001 reporting.

Note 2 - Related Party Transactions

The  Registrant  has  transactions  in the normal  course of business with other
Ameren  subsidiaries.  These  transactions  are  primarily  comprised  of  power
purchases and sales,  including power  purchases  derived under the Power Supply
Agreement between the Registrant and Marketing Company, and services received or
rendered.   Intercompany  receivables  included  in  other  accounts  and  notes
receivable were  approximately $17 million and $8 million,  respectively,  as of
September  30, 2001 and  December 31, 2000.  Intercompany  payables  included in
accounts  and  wages  payable  totaled   approximately   $79  and  $75  million,
respectively, as of September 30, 2001 and December 31, 2000.

Other  operating  expenses  consist  primarily  of  wages,   employee  benefits,
professional  services and expenses associated with support services provided by
Ameren Services.  The support services  provided by Ameren Services are based on
actual costs incurred. For each of the three months ended September 30, 2001 and
2000, other operating  expenses  provided by Ameren Services totaled $13 million
and $10 million,  respectively.  For each of the nine months ended September 30,
2001 and 2000, support services provided by Ameren Services totaled $41 million.
For each of the 12 months ended  September 30, 2001 and 2000,  support  services
provided by Ameren Services totaled $51 million and $57 million, respectively.

In addition,  the Registrant has the ability to borrow up to approximately  $899
million from Ameren,  AmerenUE or Ameren Services through a regulated money pool
agreement.  The total amount  available to the Registrant at any given time from
the  regulated  money pool is reduced by the amount of borrowings by AmerenUE or
Ameren  Services,  but increased to the extent  AmerenUE or Ameren Services have
surplus funds and the  availability  of other external  borrowing  sources.  The
regulated  money pool was  established  to  coordinate  and  provide for certain
short-term cash and working capital requirements of the Registrant, AmerenUE and
Ameren Services and is administered by Ameren  Services.  Interest is calculated
at varying  rates of interest  depending  on the  composition  of  internal  and
external funds in the regulated money pool. For the three months and nine months
ended September 30, 2001, the average interest rate for the regulated money pool
was 3.67 percent and 4.51 percent,  respectively. For each of the quarters ended
September 30, 2001 and 2000, intercompany interest expense totaled approximately
$.2 million and $2 million,  respectively.  For each of the  nine-month  periods
ended  September  30,  2001 and  2000,  intercompany  interest  expense  totaled
approximately  $4 million and $6 million,  respectively.  Intercompany  interest
expense totaled approximately $6 million and $7 million,  respectively,  for the
12 months  ended  September  30,  2001 and 2000.  At  September  30,  2001,  the
Registrant  had $29  million of  intercompany  borrowings  outstanding  and $399
million  available  through the  regulated  money pool subject to reduction  for
borrowings by AmerenUE or Ameren Services.

In  conjunction   with  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 September  30, 2001,  the  Registrant's  deferred tax  liability  and
intercompany tax receivable was $199 million.

                                       14
<PAGE>

The Registrant's intercompany note receivable from Generating Company related to
the  Transfer  totaled   approximately  $469  million  at  September  30,  2001.
Intercompany  interest  income for the three  months,  nine months and 12 months
ended September 30, 2001 totaled  approximately $9 million,  $28 million and $38
million, respectively.

Note 3 - Midwest ISO and Alliance RTO

In the  fourth  quarter of 2000,  the  Registrant  announced  its  intention  to
withdraw from the Midwest  Independent System Operator (Midwest ISO) and to join
the Alliance Regional Transmission  Organization  (Alliance RTO), and recorded a
pretax charge to earnings of $8 million ($5 million after taxes),  which related
to the  Registrant's  estimated  obligation  under the Midwest ISO agreement for
costs  incurred by the Midwest  ISO,  plus  estimated  exit costs.  During first
quarter 2001, the FERC conditionally approved the formation,  including the rate
structure,  of the Alliance RTO, and the Registrant announced that it had signed
an agreement to join the Alliance  RTO.  Also in the first  quarter  2001,  in a
proceeding  before the FERC,  the  Alliance  RTO and the  Midwest ISO reached an
agreement  that would enable the Registrant to withdraw from the Midwest ISO and
to join the  Alliance  RTO.  In the  second  quarter  of 2001,  this  settlement
agreement was approved by the FERC.  Additional regulatory approvals of the SEC,
FERC  and  the ICC may be  required  in  connection  with  various  transactions
involving the Alliance RTO relating to its organization,  capitalization and the
possible transfer of transmission assets. Such approvals,  if required,  will be
sought at the appropriate  times. The Alliance RTO is expected to be operational
within 90-120 days after the FERC's  approval.  At this time,  the Registrant is
unable to determine the impact that its withdrawal  from the Midwest ISO and its
participation in the Alliance RTO will have on its future  financial  condition,
results of operations or liquidity.

Note 4 - Derivative Financial Instruments

Statement of Financial  Accounting  Standards  (SFAS) No. 133,  "Accounting  for
Derivative  Instruments and Hedging  Activities"  became effective on January 1,
2001.  SFAS 133  establishes  accounting and reporting  standards for derivative
financial  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. The intended use of the derivatives and their  designation as either
a fair  value  hedge,  a cash flow  hedge,  or a  foreign  currency  hedge  will
determine  when the gains or losses on the  derivatives  are to be  reported  in
earnings and when they are to be reported as a component of other  comprehensive
income in stockholder's  equity.  SFAS 133 did not have a material impact on the
Registrant's financial position or results of operations upon adoption or during
the three and nine months ended September 30, 2001.

                                       15
<PAGE>

Note 5 - Segment Information
<TABLE>
<CAPTION>

Segment  information for the three-month,  nine-month and 12-month periods ended
September 30, 2001 and 2000 is as follows:
<S>                                       <C>     <C>         <C>         <C>

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

Three months ended September 30, 2001:
Revenues                                 $ 210,353   $  18,808   $     106   $ 229,267
Operating Income                            25,114      (1,242)        106      23,978
--------------------------------------------------------------------------------------

Three months ended September 30, 2000:
Revenues                                 $ 197,405   $  21,843          --   $ 219,248
Operating Income                            27,175       3,819          --      30,994
--------------------------------------------------------------------------------------

Nine months ended September 30, 2001:
Revenues                                 $ 529,455   $ 130,603   $     300   $ 660,358
Operating Income                            39,048       4,949         300      44,297
--------------------------------------------------------------------------------------

Nine months ended September 30, 2000:
Revenues                                 $ 569,239   $ 100,455          --   $ 669,694
Operating Income                            77,615      11,298          --      88,913
--------------------------------------------------------------------------------------

12 months ended September 30, 2001:
Revenues                                 $ 677,343   $ 206,919   $     300   $ 884,562
Operating Income                            38,468       8,429         300      47,197
--------------------------------------------------------------------------------------

12 months ended September 30, 2000:
Revenues                                 $ 747,686   $ 125,352          --   $ 895,433
Operating Income                           119,358       8,437          --     127,795
--------------------------------------------------------------------------------------
</TABLE>

                                       16

<PAGE>


                           PART II - OTHER INFORMATION


ITEM 5.  OTHER INFORMATION.

     The  following  material  organizational  changes  have been made to senior
management by the Board of Directors of the Registrant:

     o    Warner L. Baxter was elected Senior Vice President, Finance, effective
          August 30, 2001.

     o    Jerre E. Birdsong was elected Vice President and Treasurer,  effective
          October 12, 2001.

     o    Martin J. Lyons was appointed Controller,  effective October 22, 2001,
          replacing Warner L. Baxter.

ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K.

         (a)     Exhibits.

                 12      - Computation of Ratio of Earnings to Fixed Charges
                         and Preferred Stock Dividend Requirements, 12 months
                         Ended September 30, 2001.

         (b)     Reports on Form 8-K. None.

         Note: Reports of Ameren  Corporation on Forms 8-K, 10-Q and 10-K are on
               file with the SEC under File Number 1-4756.


                                   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
                                  Senior Vice President, Finance
                                   (Principal Financial Officer)


Date:   November 14, 2001




                                       17
<PAGE>

<TABLE>
<CAPTION>
                                                                                                    Exhibit 12

                     CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
                COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
                    AND PREFERRED STOCK DIVIDEND REQUIREMENTS

                                                                                                     12 Months
                                                                                                       Ended
                                                 Year Ended December 31,                            September 30,
                                            ------------------------------------------------------------------------


                                                   1996       1997       1998       1999       2000       2001

                                              Thousands of Dollars Except Ratios

<S>                                            <C>        <C>        <C>        <C>        <C>        <C>
Net Income                                       $ 77,393   $ 38,620   $ 80,147   $ 53,980   $ 79,362   $ 47,367
Add- Extraordinary items net of tax                  --       24,853       --         --         --         --
                                                 --------   --------   --------   --------   --------   --------
Net income from continuing operations              77,393     63,473     80,147     53,980     79,362     47,367

   Taxes based on income                           47,286     33,922     45,412     30,763     43,661     23,752
                                                 --------   --------   --------   --------   --------   --------

Net income before income taxes                    124,679     97,395    125,559     84,743    123,023     71,119
                                                 --------   --------   --------   --------   --------   --------


Add- fixed charges:
   Interest on long term debt                      31,409     32,271     37,260     38,223     28,935     31,056
   Other interest                                   4,636      2,875      1,647      3,373      8,497      7,145
   Amortization of net debt premium, discount,
      expenses and losses                           1,709      1,643      1,132      1,139      2,880      2,790

                                                 --------   --------   --------   --------   --------   --------
Total fixed charges                                37,754     36,789     40,039     42,735     40,312     40,991
                                                 --------   --------   --------   --------   --------   -----

Earnings available for fixed charges              162,433    134,184    165,598    127,478    163,335    112,110
                                                 ========   ========   ========   ========   ========   ========


Ratio of earnings to fixed charges                   4.30       3.64       4.13       2.98       4.05       2.73
                                                 ========   ========   ========   ========   ========   ========

Earnings required for preferred dividends:
   Preferred stock dividends                        3,721      3,715      3,745      3,833      3,882      3,803
   Adjustment to pre-tax basis                      2,273      1,985      2,122      2,185      2,135      1,905
                                                 --------   --------   --------   --------   --------   --------
                                                    5,994      5,700      5,867      6,018      6,017      5,708

Fixed charges plus preferred stock dividend
    requirements                                   43,748     42,489     45,906     48,753     46,329     46,699
                                                 ========   ========   ========   ========   ========   ========

Ratio of earnings to fixed charges plus
    preferred stock dividend requirements            3.71       3.15       3.60       2.61       3.52       2.40
                                                 ========   ========   ========   ========   ========   ========


</TABLE>