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                                  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 June 30, 1999

[  ]     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, 1999:  Common  Stock,  no par value,  held by Ameren  Corporation  (parent
 company of Registrant) - 25,452,373


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                     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                                         6

            Balance Sheet
            - June 30, 1999 and December 31, 1998                     8

            Statement of Income
            - Three months, six months and 12 months ended
               June 30, 1999 and 1998                                 9

            Statement of Cash Flows
            - Six months ended June 30, 1999 and 1998                10

            Notes to Financial Statements                            11


Part II     Other Information                                        14


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                    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  wholly-owned  subsidiaries  of Ameren (the
Merger).

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 1998 Form 10-K.

RESULTS OF OPERATIONS

Earnings
Second  quarter  1999  earnings of $20 million  increased $1 million from 1998's
second  quarter  earnings.  Earnings  for the six  months  ended  June 30,  1999
increased $3 million from the year-ago  period to $33 million.  Earnings for the
12 months ended June 30, 1999 were $80 million,  a $40 million increase from the
preceding  12-month period.  Excluding the extraordinary  charge recorded in the
fourth quarter of 1997 to write off the generation-related regulatory assets and
liabilities  of the  Registrant's  retail  electric  business,  earnings for the
12-month period ended June 30, 1998 were $65 million.

Earnings  fluctuated  due to many  conditions,  primarily:  weather  variations,
electric rate reductions,  competitive market forces, sales growth,  fluctuating
operating costs,  merger-related expenses,  changes in interest expense, changes
in income and property taxes, a charge for a targeted  employee  separation plan
and an extraordinary charge, as noted above.

The  significant  items  affecting  revenues,  costs  and  earnings  during  the
three-month,  six-month  and 12-month  periods  ended June 30, 1999 and 1998 are
detailed below.

Electric Operations

Electric Operating Revenues          Variations for periods ended June 30, 1999
                                         from comparable prior-year periods
--------------------------------------------------------------------------------
(Millions of Dollars)               Three Months   Six Months    Twelve Months
--------------------------------------------------------------------------------
Rate variations                      $  (3)          $  (6)         $ (11)
Effect of abnormal weather             (15)            (14)            (9)
Growth and other                         7               7              6
Interchange sales                       22              30             40
--------------------------------------------------------------------------------
                                     $  11           $  17          $  26
--------------------------------------------------------------------------------


Electric  revenues  for the three  months  and six months  ended June 30,  1999,
increased $11 million and $17 million, respectively,  compared to the comparable
year-ago periods  primarily due to increases in interchange  sales of 43 percent
and 53 percent,  respectively,  due to strong marketing efforts. These increases
were  partially  offset by  decreases in native sales during the three month and
six month  periods of 10 percent and 5 percent,  respectively,  primarily due to
milder  weather.  In addition,  electric  revenues were reduced as a result of a
residential  rate decrease (see Note 5 under Notes to Financial  Statements  for
further information).

                                      -2-

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Electric  revenues for the 12 months ended June 30, 1999,  increased $26 million
compared to the prior 12-month period, primarily driven by a 31 percent increase
in  interchange  sales,  due to strong  marketing  efforts.  This  increase  was
partially  offset by a 1 percent decline in native sales. In addition,  electric
revenues  were reduced as a result of a  residential  rate  decrease (see Note 5
under to Notes to Financial Statements for further information).

Fuel and Purchased Power
                                      Variations for periods ended June 30, 1999
                                           from comparable prior-year periods
--------------------------------------------------------------------------------
(Millions of Dollars)                    Three Months  Six Months  Twelve Months
--------------------------------------------------------------------------------
Fuel:
    Variation in generation                $  (4)        $   8         $  (3)
    Price                                     (7)          (12)          (18)
    Generation efficiencies and other          2            (2)           (7)
Purchased power variation                     14            16            26
--------------------------------------------------------------------------------
                                           $   5          $ 10          $ (2)
--------------------------------------------------------------------------------


Fuel and  purchased  power costs for the three  months and six months ended June
30,  1999,  increased  $5  million  and $10  million,  respectively,  versus the
prior-year  periods,  primarily due to an overall net increase in generation and
purchased  power resulting from higher sales volume,  partially  offset by lower
fuel prices.  The $2 million  decrease in fuel and purchased power costs for the
12 months ended June 30, 1999 versus the  prior-year  period was  primarily  the
result of lower fuel  prices,  partially  offset by  increased  purchased  power
resulting from higher sales volume.

Gas Operations
Gas  revenues  for the three month and six month  periods  ended June 30,  1999,
decreased  $4 million and $2  million,  respectively,  compared to the  year-ago
periods  primarily due to decreased retail sales,  partially offset by an annual
$8 million Illinois gas rate increase  effective February 1999. Gas revenues for
the 12-month period ended June 30, 1999,  decreased $18 million  compared to the
same year-ago period primarily due to a decline in retail sales.

Gas costs for the three months and six months ended June 30, 1999,  decreased $5
million and $4 million,  respectively,  compared to the year-ago  periods due to
lower  sales.  Gas costs for the 12 months ended June 30,  1999,  decreased  $24
million  compared to the year-ago period  primarily due to lower sales and lower
gas prices.

Other Operating Expenses
Other operating expense variations  reflected  recurring factors such as growth,
inflation, labor and benefit increases.

Other operations expenses increased $5 million and $4 million, respectively, for
the three  months  and six  months  ended June 30,  1999,  compared  to the same
year-ago periods primarily due to increased  injuries and damages expenses based
on claims experience,  and expenses associated with deregulation in Illinois and
the year 2000 project.  Other operations  expenses increased $18 million for the
12 months ended June 30, 1999,  compared to the same year-ago period,  primarily
due to the charge for the  targeted  separation  plan and  increases in expenses
associated with deregulation in Illinois and the year 2000 project.

Maintenance  expenses for the three months,  six months and 12 months ended June
30, 1999,  increased $5 million, $9 million and $3 million,  respectively,  from
the  comparable   year-ago  periods  due  to  increased  scheduled  power  plant
maintenance.

Other Taxes
Other taxes decreased  primarily due to a decrease in gross receipt taxes.  This
decrease  results  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.

                                      -3-

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Taxes
Income taxes for the six months and 12 months ended June 30, 1999,  increased $2
million and $12 million, respectively, primarily due to higher pretax income.

Balance Sheet
Changes in accounts and wages payable,  taxes accrued,  other accruals and other
current  assets  resulted  from  the  timing  of  various   payments  to  taxing
authorities  and  suppliers.  The $128 million  increase in  intercompany  notes
payable  is due to funds  borrowed  from a utility  money pool (see Note 6 under
Notes to Financial Statements for further information).

LIQUIDITY AND CAPITAL RESOURCES

Cash  provided by  operating  activities  totaled $80 million for the six months
ended June 30, 1999, compared to $59 million during the same 1998 period.

Cash flows used in investing activities were $62 million and $29 million for the
six months ended June 30, 1999 and 1998, respectively. Construction expenditures
for the six months  ended  June 30,  1999,  for  constructing  new or  improving
existing facilities were $63 million.  Capital requirements for the remainder of
1999 are expected to be principally for construction expenditures.

Cash flows used in  financing  activities  were $10  million  for the six months
ended June 30, 1999,  compared to $46 million  during the same 1998 period.  The
Registrant's  principal  financing  activities  for  the  quarter  included  the
redemption  of $102  million  of debt and the  payment of  dividends,  partially
offset by the issuance of intercompany notes payable.

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 10 to 45 days). At June 30,
1999, the Registrant had committed bank lines of credit  aggregating $30 million
(all of which were  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, 1999, the Registrant
had no outstanding short-term borrowings other than $128 million of intercompany
notes payable.

Also,  Ameren has a bank credit  agreement due 2002, which permits the borrowing
of up to $200 million on a long-term  basis.  This credit agreement is available
to Ameren and its subsidiaries,  including the Registrant.  As of June 30, 1999,
$158 million was available for the Registrant's use.

RATE MATTERS

In March 1999, the Registrant  filed delivery  service tariffs with the Illinois
Commerce  Commission  (ICC) to  comply  with the  requirements  of the  Electric
Service Customer Choice and Rate Relief Law of 1997. These tariffs would be used
by  electric  customers  who choose to purchase  their  power from an  alternate
supplier.  Hearings  were  conducted  in June  1999,  and a  hearing  examiner's
proposed  order was issued in July.  The ICC is required to render a decision on
the delivery services tariffs by September 1, 1999.

See Note 5 under Notes to Financial  Statements  for further  discussion of Rate
Matters.

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 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 supplier.
The  phase-in  of retail  direct  access  begins on October 1, 1999,  with large
commercial and industrial  customers  principally  comprising the initial group.
The customers in this group

                                      -4-

<PAGE>

represent  approximately  24 percent of the  Registrant's  total  sales.  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.

In conjunction with another provision of the Law, in July 1999, AmerenCIPS filed
a  notice  with the ICC  that it  intends  to  transfer  AmerenCIPS'  generating
facilities  (all in Illinois) to a new  unregulated  subsidiary  of Ameren.  The
formation  of  the  new  generating  subsidiary,  as  well  as the  transfer  of
AmerenCIPS' generating assets and liabilities (at historical net book value) and
certain  power  sales  contracts,  will be  subject to  regulatory  proceedings.
Regulatory  approvals are required from the ICC, the Federal  Energy  Regulatory
Commission,   and  the  Missouri  Public  Service  Commission.   The  generating
subsidiary will include eight new combustion  turbine  generators being acquired
by Ameren in  addition  to the  AmerenCIPS  facilities.  The new  subsidiary  is
expected to be  operational  sometime  in 2000,  subject to the outcome of these
regulatory proceedings.

Once the  transfer is  completed,  a power  supply  agreement  would be in place
between the new generating company and a nonregulated  marketing  subsidiary for
all generation.  The marketing  subsidiary  would have a power supply  agreement
with  AmerenCIPS  to supply  them  sufficient  generation  to meet  native  load
requirements  over the term of the agreement.  Power will continue to be jointly
dispatched between AmerenUE, AmerenCIPS and the new generating subsidiary.

The proposed  transfer of generating assets and liabilities had no effect on the
Registrant's financial statements as of June 30, 1999.

YEAR 2000 ISSUE

The Year  2000  Issue  relates  to how  dates are  stored  and used in  computer
systems,  applications, and embedded systems. As the century date change occurs,
certain date-sensitive systems need to be able to recognize the year as 2000 and
not as 1900. This inability to recognize and properly treat the year as 2000 may
cause these systems to process  critical  financial and operational  information
incorrectly.   The  Registrant's  primary  concern  is  the  potential  for  any
interruption in providing electric and gas service to customers,  as well as the
potential inability to process critical financial and operational information on
a timely basis,  including  billing its customers,  if appropriate steps are not
taken to address this issue.  Management  has  developed a Year 2000 plan (Plan)
covering Ameren, including AmerenCIPS,  and Ameren's Board of Directors has been
briefed about the Year 2000 Issue and how it may affect the Registrant.

Ameren's Plan to resolve the Year 2000 Issue involves three phases:  assessment,
planning,  and implementation/  testing.  Implementation of the Plan is directly
supervised  by each  area's  responsible  Vice  President.  A Year 2000  Project
Director  coordinates the  implementation of the Plan among functional teams who
are  addressing  issues  specific  to a  particular  area,  such as nuclear  and
non-nuclear generation facilities,  energy management systems, gas distribution,
etc. Ameren has also engaged certain outside consultants,  technicians and other
external resources to aid in formulating and implementing the Plan.

Ameren  has  completed  its   assessment   phase,   which   included   analyzing
date-sensitive  electronic hardware,  software applications and embedded systems
and has developed a compliance plan to address issues that were identified. Many
of the major  corporate  computer  systems  at  Ameren  are  relatively  new and
therefore are either Year 2000  compliant or only require  minor  modifications.
Also,   several  of  the  operating   hardware  and  embedded   systems   (i.e.,
microprocessor  chips) use analog  rather than digital  technology  and thus are
unaffected  by the  two-digit  date issue.  In  addition,  Ameren has  contacted
hundreds of vendors and suppliers to verify compliance.

Ameren has also completed its planning  phase.  Items that have been  identified
for remediation have been prioritized into groups based on their significance to
Ameren's    operations.    The    implementation/testing     phase    for    all
components/applications  is  approximately  87 percent  complete  as of June 30,
1999.   Ameren   expects   to   complete    remediation   of   its   significant
components/applications by the end of the third quarter 1999.

With  respect  to  third  parties,   for  areas  that  interface  directly  with
significant  vendors,  Ameren has inventoried vendors and major suppliers and is
currently  assessing  their Year 2000 readiness  through  surveys,  websites and
personal contact. Ameren plans to follow up with major suppliers and vendors and
verify Year 2000  compliance,  where  appropriate.  Ameren has also  queried its
health insurance  providers.  To date,  Ameren is not aware of any problems that
would  materially  impact its  financial  condition,  results of  operations  or
liquidity.  However, neither Ameren nor the Registrant has the means of ensuring
that these parties will be Year 2000  compliant.  The inability of those parties
to complete their Year 2000 resolution  process could  materially  impact Ameren
and the Registrant.

                                      -5-


<PAGE>

Ameren is also  addressing  the impact of electric  power grid problems that may
occur outside of its own electric system.  Ameren has started Year 2000 electric
power grid impact planning through the system's various electric interconnection
affiliations and is working with the Mid-American  Interchange Network (MAIN) to
begin planning Year 2000 operational  preparedness and restoration scenarios. As
of July 1, 1999 (the  latest  information  available),  MAIN had  completed  its
assessment   and  planning   phases  and  was  99  percent   complete  with  its
implementation/  testing  phase.  In addition,  Ameren  provides  monthly status
reports to the North American Electric Reliability Council (NERC) to assist them
in assessing  Year 2000  readiness of the regional  electric grid. As of July 1,
1999 (the latest information  available),  NERC had completed its assessment and
planning  phases and was 98  percent  complete  with its  implementation/testing
phase.  The Registrant  participated  in a Year 2000 drill  conducted by NERC in
April 1999.  The drill focused on the testing of the backup systems of voice and
data communications needed to operate the electric power grids in the event of a
partial  communication loss. The results of the drill at Ameren were successful.
Additional  drills are planned.  Through the Electric Power  Research  Institute
(EPRI),  an  industry-wide  effort has been  established  to deal with Year 2000
problems  affecting  digital systems and equipment used by the nation's electric
power companies. Under this effort, participating utilities are working together
to assess specific  vendors' system problems and test plans. The assessment will
be shared by the industry as a whole to facilitate Year 2000 problem solving.

In addressing  the Year 2000 Issue,  Ameren will incur  internal  labor costs as
well as  external  consulting  and  other  expenses  related  to  infrastructure
enhancements necessary to prepare for the new century. Ameren estimates that its
external costs  (consulting fees and related costs) for addressing the Year 2000
Issue will range from $10 million to $15 million.  As of June 30,  1999,  Ameren
had expended  approximately  $7 million.  Ameren's  plans to complete  Year 2000
modifications  are based on  management's  best  estimates,  which  are  derived
utilizing  numerous   assumptions  of  future  events  including  the  continued
availability of certain resources,  and other factors.  However, there can be no
guarantee that these  estimates will be achieved and actual results could differ
materially  from those plans.  Specific  factors that might cause such  material
differences  include,  but are not  limited  to,  the  availability  and cost of
personnel  trained in this area,  the ability to locate and correct all relevant
computer codes, and similar uncertainties.

Ameren  believes  that,  with  appropriate  modifications  to existing  computer
systems/components,  updates by vendors and trading partners,  and conversion to
new  software and  hardware in the  ordinary  course of business,  the Year 2000
Issue  will  not  pose  significant  operational  problems  for the  Registrant.
However,  if such conversions are not completed in a proper and timely manner by
all  affected  parties,  the Year 2000 Issue could  result in  material  adverse
operational and financial  consequences  to the Registrant,  and there can be no
assurance  that  Ameren's  efforts,  or those of vendors and  trading  partners,
interconnection  affiliates, NERC or EPRI to address the Year 2000 Issue will be
successful.  Ameren is in the process of developing contingency plans to address
potential risks, including risks of vendor/trading  partners  noncompliance,  as
well as noncompliance of any of the Registrant's material operating systems. The
first  operational  contingency  plan addressing power grid issues was completed
during the first  quarter of 1999.  Contingency  plans  related to the  business
areas were  completed in July 1999.  At this time,  the  Registrant is unable to
predict the ultimate impact,  if any, of the Year 2000 Issue on the Registrant's
financial  condition,  results of operations or liquidity;  however,  the impact
could be material.

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 interest  rates and
equity prices.  The following  discussion of 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.  The  Registrant  handles  market  risks  in
accordance with  established  policies,  which may include entering into various
derivative  transactions.  In the normal course of business, the Registrant also
faces  risks  that are  either  non-financial  or  non-quantifiable.  Such risks
principally  include  credit risk and legal 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,
fixed-rate  debt,  commercial  paper and auction  market  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  1  percent  in  2000 as  compared  to  1999,  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, 1999,  continued to be outstanding
throughout 2000, and that the average interest rates for these instruments

                                       -6-

<PAGE>

increased 1 percent  over 1999.  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  purchased  power.  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, the Registrant has entered into several long-term contracts
with various  suppliers to purchase  coal to manage its exposure to fuel prices.
With regard to the Registrant's  exposure to commodity risk for purchased power,
Ameren  has  established  a  subsidiary,   AmerenEnergy,   Inc.,  whose  primary
responsibility  includes  managing  market  risks  associated  with the changing
market prices for purchased power for the Registrant.

AmerenEnergy  utilizes  several  techniques  to  mitigate  its  market  risk for
purchased  power,  including  utilizing  derivative  financial  instruments.   A
derivative  is a contract  whose value is dependent on or derived from the value
of some underlying asset. The derivative financial instruments that AmerenEnergy
is allowed to utilize (which include  forward  contracts and futures  contracts)
are  dictated by a risk  management  policy,  which has been  reviewed  with the
Auditing  Committee of Ameren's  Board of  Directors.  Compliance  with the risk
management policy is the responsibility of a risk management steering committee,
consisting of Ameren  officers and an  independent  risk  management  officer at
AmerenEnergy.

As of June 30, 1999, the fair value of derivative financial  instruments exposed
to commodity  price risk was immaterial.  The Registrant  expects an increase in
the derivative financial instruments used to manage risk in 1999 due to expected
growth at AmerenEnergy.

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 and for hedging  activities and
requires  recognition  of all  derivatives on the balance sheet measured at fair
value.  In June 1999,  the FASB  issued  SFAS 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. Earlier  application
is still  encouraged.  At this time,  the  Registrant is unable to determine the
impact of SFAS 133 on its  financial  position  or  results of  operations  upon
adoption;  however,  SFAS 133 could increase the volatility of the  Registrant's
future earnings.

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.
Factors  include,  but are not limited to, the  effects of  regulatory  actions;
changes  in laws and other  governmental  actions;  competition;  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;  monetary  and fiscal
policies; future wages and employee benefits costs; and legal and administrative
proceedings.

                                      -7-

<PAGE>


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

<TABLE>
<CAPTION>

                                                                 June 30,    December 31,
ASSETS                                                             1999         1998
------                                                          ----------   ----------
<S>                                                           <C>          <C>
Property and plant, at original cost:
   Electric                                                     $2,398,065   $2,381,682
   Gas                                                             263,305      259,656
                                                                ----------   ----------
                                                                 2,661,370    2,641,338
   Less accumulated depreciation and amortization                1,229,856    1,192,108
                                                                ----------   ----------
                                                                 1,431,514    1,449,230
Construction work in progress                                       54,024       16,220
                                                                ----------   ----------
         Total property and plant, net                           1,485,538    1,465,450

Other assets                                                        29,472       31,904
Current assets:
Cash and cash equivalents                                           17,300       10,180
   Accounts receivable - trade (less allowance for doubtful
         accounts of $2,560 and $1,714, respectively)               50,594       44,494
   Unbilled revenue                                                 51,461       53,120
   Other accounts and notes receivable                              25,592       16,486
   Materials and supplies, at average cost -
      Fossil fuel                                                   41,326       50,791
      Other                                                         34,702       36,047
   Other                                                             7,234        8,214
                                                                ----------   ----------
         Total current assets                                      228,209      219,332
Regulatory assets:
   Deferred income taxes                                            23,159       24,797
   Other                                                            18,685       22,914
                                                                ----------   ----------
         Total regulatory assets                                    41,844       47,711
                                                                ----------   ----------
Total Assets                                                    $1,785,063   $1,764,397
                                                                ==========   ==========

CAPITAL AND LIABILITIES
Capitalization:
   Common stock, no par value, authorized 45,000,000 shares -
     outstanding 25,452,373 shares                              $  120,033   $  120,033
   Retained earnings                                               454,552      455,337
                                                                ----------   ----------
         Total common stockholders' equity                         574,585      575,370
   Preferred stock not subject to mandatory redemption              80,000       80,000
   Long-term debt                                                  498,547      528,446
                                                                ----------   ----------
        Total capitalization                                     1,153,132    1,183,816
Current liabilities:
   Current maturity of long-term debt                               35,000       60,000
   Short-term debt                                                    --         46,700
   Intercompany notes payable                                      127,500         --
   Accounts and wages payable                                       57,048       61,609
   Accumulated deferred income taxes                                22,003       21,386
   Taxes accrued                                                    18,357       13,201
   Other                                                            33,068       34,454
                                                                ----------   ----------
         Total current liabilities                                 292,976      237,350
                                                                ----------   ----------
Accumulated deferred income taxes                                  226,904      234,119
Accumulated deferred investment tax credits                         33,415       34,657
Regulatory liability                                                36,813       39,621
Other deferred credits and liabilities                              41,823       34,834
                                                                ----------   ----------
Total Capital and Liabilities                                   $1,785,063   $1,764,397
                                                                ==========   ==========

</TABLE>

See Notes to Financial Statements.

                                      -8-

<PAGE>

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


<TABLE>
<CAPTION>

                                              Three Months Ended       Six Months Ended         Twelve Months Ended
                                                   June 30,                 June 30,                  June 30,
                                              1999         1998        1999         1998          1999        1998
                                              ----         ----        ----         ----          ----        ----

 OPERATING REVENUES:
<S>                                      <C>          <C>          <C>          <C>          <C>          <C>
    Electric                               $ 200,336    $ 189,173    $ 355,576    $ 338,444    $ 739,050    $ 712,765
    Gas                                       21,593       25,656       74,125       75,900      123,731      142,031
                                           ---------    ---------    ---------    ---------    ---------    ---------
 Total operating revenues                    221,929      214,829      429,701      414,344      862,781      854,796

 OPERATING EXPENSES:
    Operations
       Fuel and purchased power               70,542       65,096      126,232      116,178      240,139      241,989
       Gas                                     9,752       14,630       43,002       46,855       65,497       89,087
       Other                                  45,581       40,857       85,979       82,151      183,305      164,922
                                           ---------    ---------    ---------    ---------    ---------    ---------
                                             125,875      120,583      255,213      245,184      488,941      495,998
    Maintenance                               25,161       20,086       42,568       33,921       80,189       77,312
    Depreciation and amortization             19,449       18,612       40,189       37,434       77,078       77,483
    Income taxes                              11,197       11,281       17,176       15,629       47,316       34,828
    Other taxes                               10,266       15,838       19,865       32,015       44,684       60,760
                                           ---------    ---------    ---------    ---------    ---------    ---------
       Total operating expenses              191,948      186,400      375,011      364,183      738,208      746,381

 OPERATING INCOME                             29,981       28,429       54,690       50,161      124,573      108,415

 OTHER INCOME AND DEDUCTIONS:
    Allowance for equity funds used
       during construction                         7            3            1           49          (32)         688
    Miscellaneous, net                           725          (65)       1,081          289         (163)      (3,002)
                                           ---------    ---------    ---------    ---------    ---------    ---------
       Total other income and deductions         732          (62)       1,082          338         (195)      (2,314)

 INCOME BEFORE
    INTEREST CHARGES                          30,713       28,367       55,772       50,499      124,378      106,101

 INTEREST CHARGES:
    Interest                                  10,343        9,271       21,158       19,703       41,494       38,632
    Allowance for borrowed funds
       used during construction                 (310)        (253)        (381)        (671)        (791)      (1,275)
                                           ---------    ---------    ---------    ---------    ---------    ---------
    Net interest charges                      10,033        9,018       20,777       19,032       40,703       37,357

 INCOME BEFORE
    EXTRAORDINARY CHARGE                      20,680       19,349       34,995       31,467       83,675       68,744
                                           ---------    ---------    ---------    ---------    ---------    ---------
 EXTRAORDINARY CHARGE
   (NET OF INCOME TAXES)                        --           --           --           --           --        (24,853)
                                           ---------    ---------    ---------    ---------    ---------    ---------

NET INCOME                                    20,680       19,349       34,995       31,467       83,675       43,891

PREFERRED STOCK DIVIDENDS                        917          881        1,885        1,865        3,765        3,739
                                           ---------    ---------    ---------    ---------    ---------    ---------
NET INCOME AFTER PREFERRED
   STOCK DIVIDENDS                         $  19,763    $  18,468    $  33,110    $  29,602    $  79,910    $  40,152
                                           =========    =========    =========    =========    =========    =========

</TABLE>

See Notes to Financial Statements.

                                      -9-

<PAGE>

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

<TABLE>
<CAPTION>


                                                            Six Months Ended
                                                               June 30,
                                                           1999         1998
                                                           ----         ----
Cash Flows From Operating:
<S>                                                  <C>          <C>
   Net income                                          $  34,995    $  31,467
   Adjustments to reconcile net income to net cash
      provided by operating activities:
        Depreciation and amortization                     40,189       37,434
        Allowance for funds used during construction        (382)        (720)
        Deferred income taxes, net                        (7,768)      (6,943)
        Deferred investment tax credits, net              (1,242)      (3,049)
        Changes in assets and liabilities:
           Receivables, net                              (13,547)      (4,386)
           Materials and supplies                         10,810          (59)
           Accounts and wages payable                     (4,561)     (29,334)
           Taxes accrued                                   5,156        8,082
           Other, net                                     16,135       26,461
                                                       ---------    ---------
Net cash provided by operating activities                 79,785       58,953

Cash Flows From Investing:
   Construction expenditures                             (62,840)     (30,166)
   Allowance for funds used during construction              382          720
                                                       ---------    ---------
Net cash used in investing activities                    (62,458)     (29,446)

Cash Flows From Financing:
   Dividends on common stock                             (34,310)     (34,310)
   Dividends on preferred stock                           (1,697)      (2,080)
   Redemptions -
      Short-term debt                                    (46,700)      (9,866)
      Long-term debt                                     (55,000)     (10,000)
   Issuances -
      Long-term debt                                        --         10,000
      Intercompany notes payable                         127,500         --
                                                       ---------    ---------
Net cash used in financing activities                    (10,207)     (46,256)

Net increase (decrease) in cash and cash equivalents       7,120      (16,749)
Cash and cash equivalents at beginning of year            10,180       28,140
                                                       ---------    ---------
Cash and cash equivalents at end of period             $  17,300    $  11,391
                                                       =========    =========

Cash paid during the periods:
   Interest (net of amount capitalized)                $  19,458    $  19,530
   Income taxes, net                                   $  21,805    $  18,426

</TABLE>

See Notes to Financial Statements.

                                      -10-

<PAGE>

CENTRAL ILLINOIS PUBLIC SERVICE COMPANY
NOTES TO FINANCIAL STATEMENTS (UNAUDITED)
June 30, 1999


Note 1 - Central Illinois Public Service Company  (AmerenCIPS or the Registrant)
is a wholly-owned subsidiary of Ameren Corporation (Ameren), which is the parent
company of two utility  operating  companies,  the Registrant and Union Electric
Company  (AmerenUE).  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  Corporation  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-owned 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% 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.

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
Securities and Exchange  Commission.  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 1998
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, 1999 and 1998 are not  necessarily  indicative  of trends for any
three-month, six-month or 12-month period.

Note 5 -In conjunction with the Electric Service Customer Choice and Rate Relief
Law of 1997 (the Law), a 5 percent  residential  electric  rate decrease for the
Registrant's electric customers was effective August 1, 1998. This rate decrease
is  expected to  decrease  electric  revenues  $11  million  annually,  based on
estimated levels of sales and assuming normal weather conditions. The Registrant
may be subject to additional 5 percent  residential  electric rate  decreases in
each of 2000 and 2002,  to the  extent  its rates  exceed  the  Midwest  utility
average at that time.  The  Registrant's  rates are currently  below the Midwest
utility average.

The Law also contains a provision requiring one-half of excess earnings from the
Illinois  jurisdiction  for the years 1998  through  2004 to be  refunded to the
Registrant's  customers.  Excess  earnings  are  defined  as the  portion of the
two-year average annual rate of return on common equity in excess of 1.5 percent
of the two-year average of an Index, as defined in the Law. The Index is defined
as the sum of the  average  for the  twelve  months  ended  September  30 of the
average  monthly  yields of the  30-year U. S.  Treasury  bonds plus  prescribed
percentages  ranging from 4 percent to 5 percent.  In July 1999,  Senate Bill 24
was passed which increased the prescribed  percentages to 7 percent beginning in
2000.  Filings must be made with the ICC on or before March 31 of each year 2000
through 2005. At this time,  the Registrant is unable to determine the amount of
the credit it will be required to return to customers, if any, under the Law for
the two year period ended December 31, 1999.

                                      -11-

<PAGE>

Note 6 - 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  $18 million
and $2  million,  respectively,  as of June 30,  1999  and  December  31,  1998.
Intercompany   payables   included  in  accounts  and  wages   payable   totaled
approximately $12 million as of June 30, 1999 and December 31, 1998.

In March 1999, the Registrant,  along with Ameren Services Company and AmerenUE,
entered  into a utility  money pool  agreement  to  coordinate  and  provide for
certain short-term cash and working capital  requirements.  Borrowings under the
agreement  are  limited to $500  million  and are due on demand or within in one
year.  Interest is calculated at varying rates  depending on the  composition of
internal and external funds in the money pool. The money pool is administered by
Ameren Services Company. The Registrant recorded an intercompany note payable of
$128 million, representing funds borrowed from the utility money pool as of June
30, 1999.

Note 7 - Statement of Position (SOP) 98-1, "Accounting for the Costs of Computer
Software  Developed or Obtained for Internal Use" became effective on January 1,
1999.  SOP 98-1  provides  guidance  on  accounting  for the  costs of  computer
software  developed or obtained for internal use. Under SOP 98-1, certain costs,
may be capitalized and amortized over some future period.  SOP 98-1 did not have
a  material  impact  on  the  Registrant's  financial  position  or  results  of
operations upon adoption.

The  Emerging  Issues Task Force of the  Financial  Accounting  Standards  Board
(EITF)  Issue  98-10,   "Accounting  for  Energy  Trading  and  Risk  Management
Activities" became effective on January 1, 1999. EITF 98-10 provides guidance on
the  accounting  for energy  contracts  entered into for the purchase or sale of
electricity,  natural  gas,  capacity  and  transportation.  The EITF  reached a
consensus in EITF 98-10 that sales and purchase  activities being performed need
to be classified as either  trading or  non-trading.  Furthermore,  transactions
that are determined to be trading  activities would be recognized on the balance
sheet measured at fair value,  with gains and losses included in earnings.  EITF
98-10  includes  factors  or  indicators  to  consider  when  determining  if  a
transaction is a trading or non-trading activity. Currently, AmerenEnergy, Inc.,
an energy marketing subsidiary of Ameren, enters into contracts for the sale and
purchase of energy on behalf of AmerenCIPS.  These  transactions  are considered
non-trading  activities  and are  accounted  for using the accrual or settlement
method, which represents industry practice.  Should any of AmerenEnergy's future
activities be considered  material  trading  activities  based on the indicators
provided in EITF 98-10, a change in accounting practice would be required.  EITF
98-10 did not have a material impact on the Registrant's  financial  position or
results of operations upon adoption.

                                      -12-

<PAGE>

Note 8 - Segment information for the three month, six month and 12 month periods
ended June 30, 1999 and 1998 is as follows:

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

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

Three months ended June 30, 1999:

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

Three months ended June 30, 1998:

Revenues                                 $189,173   $ 25,656   $214,829
Operating Income (Net)                     27,922        507     28,429
------------------------------------------------------------------------
Six months ended June 30, 1999:

Revenues                                 $355,576   $ 74,125   $429,701
Operating Income (Net)                     48,419      6,271     54,690
------------------------------------------------------------------------
Six months ended June 30, 1998:

Revenues                                $338,444   $ 75,900    $414,344
Operating Income (Net)                    46,926      3,235      50,161
------------------------------------------------------------------------
12 months ended June 30, 1999:

Revenues                                $739,050   $123,731    $862,781
Operating Income (Net)                   116,476      8,097     124,573
------------------------------------------------------------------------
12 months ended June 30, 1998:

Revenues                                $712,765   $142,031    $854,796
Operating Income (Net)                   103,091      5,324     108,415
------------------------------------------------------------------------

Note 9 - Certain  reclassifications were made to prior-year financial statements
to conform to current-period presentation.

                                      -13-

<PAGE>

                           PART II. OTHER INFORMATION


ITEM 1.  LEGAL PROCEEDINGS

         Reference  is  made  to  Item  3.  Legal  Proceedings  and  Note  10  -
Commitments  and  Contingencies  in the  Notes to  Financial  Statements  of the
Registrant's  Form 10-K for the year ended  December  31,  1998 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. In April 1999, the unions
filed  petitions  for review with the U.S.  Court of Appeals for the District of
Columbia  Circuit of the NLRB's August 1998 decision which ruled in favor of the
Registrant and held that the lockout was lawful.

         Reference  is made to  "Liquidity  and  Capital  Resources"  in Item 7.
Management's  Discussion  and  Analysis of Financial  Conditions  and Results of
Operations and Note 10 - Commitments and  Contingencies of the Registrant's Form
10-K for the year ended December 31, 1998 for  information  regarding the United
States  Environmental  Protection  Agency's  (EPA)  issuance in 1997 of National
Ambient Air Quality Standards for ozone and particulate matter. In May 1997, the
United States Court of Appeals for the District of Columbia Circuit remanded the
ambient air quality  standards  to EPA 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 operations or liquidity.
In further reference to Note 10 - Commitments and Contingencies,  the Registrant
has been  designated  as a  potentially  responsible  party by federal and state
environmental protection agencies at five hazardous waste sites.


ITEM 5.  OTHER INFORMATION

         Reference is made to Note 10 -  Commitments  and  Contingencies  in the
Notes to Financial  Statements of the Registrant's  Form 10-K for the year ended
December 31, 1998 for  information  concerning the expiration date of collective
bargaining agreements. The Registrant is engaged in labor  negotiations with the
International  Brotherhood of Electrical Workers and the International  Union of
Operating Engineers and the collective  bargaining agreements have been extended
so as to facilitate those  negotiations.  At this time, the Company is unable to
predict  the impact of these  negotiations  on its future  financial  condition,
results of operations or cash flows.

         Any stockholder  proposal  intended for inclusion in the proxy material
for the Registrant's 2000 annual meeting of stockholders must be received by the
Registrant by December 1, 1999.


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

         (a)   Exhibits.

               Exhibit 12 -  Computation  of Ratio of Earnings to Fixed  Charges
               and Preferred Stock Dividend  Requirements,  12 Months Ended June
               30, 1999.

               Exhibit 27 - Financial Data Schedule.

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

                                      -14-

<PAGE>

                                   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 13, 1999

                                      -15-