<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                    FORM 10-Q

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

     For Quarterly Period Ended March 31, 2000

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

     For The Transition Period From               to

                         Commission file number 1-2967.

                             UNION ELECTRIC COMPANY
             (Exact name of registrant as specified in its charter)

            Missouri                                             43-0559760
(State or other jurisdiction of                               (I.R.S. Employer
incorporation or organization)                               Identification No.)


                 1901 Chouteau Avenue, St. Louis, Missouri 63103
              (Address of principal executive offices and Zip Code)


                         Registrant's telephone number,
                       including area code: (314) 621-3222


     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 April
  30, 2000:  Common  Stock,  $5 par value,  held by Ameren  Corporation  (parent
  company of Registrant) - 102,123,834

<PAGE>



                             Union Electric Company

                                      Index

                                                                        Page No.

Part I     Financial Information (Unaudited)

           Management's Discussion and Analysis                            2

           Quantitative and Qualitative Disclosures
           About Market Risk                                               5

           Balance Sheet
           - March 31, 2000 and December 31, 1999                          8

           Statement of Income
           - Three months and 12 months ended
              March 31, 2000 and 1999                                      9

           Statement of Cash Flows
           - Three months ended March 31, 2000 and 1999                   10

           Notes to Financial Statements                                  11


Part II    Other Information                                              13


<PAGE>

                    PART I. FINANCIAL INFORMATION (UNAUDITED)

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

OVERVIEW

Union Electric  Company  (AmerenUE 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,  AmerenUE  and CIPSCO
Incorporated  (CIPSCO)  combined to form  Ameren,  with  AmerenUE  and  CIPSCO's
subsidiaries,  Central  Illinois Public Service Company  (AmerenCIPS) and CIPSCO
Investment Company (CIC), becoming subsidiaries of Ameren (the Merger).

The following  discussion and analysis  should be read in  conjunction  with the
Notes to the  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 the  Financial  Statements
appearing in the Registrant's 1999 Form 10-K.


RESULTS OF OPERATIONS

Earnings
First quarter 2000 earnings of $37 million decreased $5 million compared to 1999
first quarter  earnings.  Earnings for the 12 months ended March 31, 2000,  were
$336  million,  a $11  million  increase  from the  preceding  12-month  period.
Earnings  fluctuated  due to many  conditions,  primarily:  weather  variations,
credits to electric  customers,  electric rate  reductions,  gas rate increases,
competitive market forces, sales growth,  fluctuating operating costs (including
Callaway Nuclear Plant refueling outages),  changes in interest expense, changes
in income and property taxes, and a nonrecurring  charge for a targeted employee
separation plan.

The  significant  items  affecting  revenues,  costs  and  earnings  during  the
three-month  and 12-month  periods ended March 31, 2000 and 1999 are detailed on
the following pages.

Electric Operations
Electric Operating Revenues          Variations for periods ended March 31, 2000
                                         from comparable prior-year periods
--------------------------------------------------------------------------------
(Millions of Dollars)                   Three Months           Twelve Months
--------------------------------------------------------------------------------
Rate variations                          $    -                 $    (4)
Credit to customers                          10                      27
Effect of abnormal weather                  (10)                    (51)
Growth and other                              3                      35
Interchange sales                            55                     171
--------------------------------------------------------------------------------
                                         $   58                   $ 178
--------------------------------------------------------------------------------

The $58 million increase in the first quarter electric  revenues compared to the
year-ago  quarter  was  primarily  driven  by a  100  percent  increase  in  the
interchange  sales due to  strong  marketing  efforts  and  greater  interchange
opportunities.  Also, contributing to the revenue increase was a decrease in the
credit to  Missouri  electric  customers  (see Note 5 under  Notes to  Financial
Statements for further information).  The decrease in native sales was primarily
due to decreased wholesale sales,  partially offset by increased residential and
commercial sales.

Electric revenues for the 12 months ended March 31, 2000 and 1999 increased $178
million  compared to the prior  12-month  period.  The  increase in revenues was
primarily  driven by a strong regional economy and increased  interchange  sales
due to  increased  interchange  opportunities.  Interchange  sales  increased 54
percent,   partially  offset  by  a  3  percent  decline  in   weather-sensitive
residential  sales.  Also contributing to the revenue increase was a decrease in
the  credit  to  Missouri  electric  customers  (see  Note 5 under  the Notes to
Financial Statements for further information).

                                      -2-

<PAGE>



Fuel and Purchased Power             Variations for periods ended March 31, 2000
                                            from comparable prior-year periods
--------------------------------------------------------------------------------
(Millions of Dollars)                        Three Months       Twelve Months
--------------------------------------------------------------------------------
Fuel:
     Generation                                $   5               $  (2)
     Price                                        (3)                  -
     Generation efficiencies and other            (3)                 (7)
Purchased power variation                         53                 178
--------------------------------------------------------------------------------
                                               $  52               $ 169
--------------------------------------------------------------------------------


The increase in fuel and purchased power costs for the three months and 12 month
periods ended March 31, 2000, compared to the year ago comparable  periods,  was
primarily due to increased  generation and purchased power resulting from higher
sales volumes.

Gas Operations
Gas revenues for the quarter ended March 31, 2000 decreased $3 million  compared
to the prior-year  period  primarily due to a 14 percent decline in retail sales
resulting from mild weather.

Gas  revenues  for the 12 months  ended  March 31,  2000  decreased  $5  million
compared to the year-ago  period  primarily due to a decline in retail sales due
to milder weather,  partially offset by an Illinois gas rate increase  effective
February 1999.

Gas costs for the 12 months ended March 31, 2000  increased $4 million  compared
to the year-ago period, primarily due to higher gas prices.

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

Other operations expenses for the three months ended March 31, 2000 increased $7
million,  compared to the same year-ago period  primarily due to increased costs
associated with the automated meter reading roll-out.  Other operations expenses
decreased  $19 million for the 12 months ended March 31,  2000,  compared to the
same year-ago  period  primarily  due to the 1998 one-time  pretax charge of $18
million for a targeted separation plan.

Maintenance  expenses for the three and 12 months ended March 31, 2000 increased
$2 million  and $24  million,  respectively,  compared to the  year-ago  periods
primarily due to increased power plant maintenance and tree trimming activity.

Taxes
Income taxes  decreased $3 million for the three months ended March 31, 2000 due
to lower  pretax  income.  Income  taxes  increased $4 million for the 12 months
ended March 31, 2000 due to higher pretax income.

Other tax expense  decreased  $12 million for the 12 months ended March 31, 2000
due primarily to a decrease in gross receipts taxes related to the  Registrant's
Illinois  jurisdiction.  This decrease is the result of the restructuring of the
Illinois  public utility tax whereby gross receipts taxes are no longer recorded
as electric revenues and gross receipts tax expense.

Balance Sheet

The $47 million  decrease in trade accounts  receivable and unbilled  revenue at
March 31, 2000, compared to the year-end, was due primarily to lower revenues in
February and March 2000  compared to November and  December  1999.  In addition,
four of the Registrant's  wholesale  customers were transferred to AmerenCIPS in
first quarter 2000. The $20 million  decrease in intercompany  notes  receivable
reflects  changes in funds invested in a regulated  money pool (see Note 6 under
Notes to Financial Statements for further information).

Changes in accounts and wages payable and other taxes accrued  resulted from the
timing of various payments to taxing authorities and suppliers.

                                      -3-

<PAGE>

The $12 million  increase in other current  liabilities was primarily due to the
$10 million  estimated  credit to Missouri  electric  customers  recorded in the
first quarter of 2000 under the three-year  experimental  alternative regulation
plan. See Note 5 under Notes to Financial Statements for further information.

The $17 million increase in other deferred credits and liabilities was primarily
due to increased accrued pension liabilities.


LIQUIDITY AND CAPITAL RESOURCES

Cash provided by operating  activities totaled $144 million for the three months
ended March 31, 2000, compared to $110 million during the same 1999 period.

Cash flows used in investing  activities totaled $84 million and $47 million for
the three  months  ended  March 31,  2000 and 1999,  respectively.  Construction
expenditures  for the three months ended March 31, 2000, for constructing new or
improving  existing  facilities were $100 million.  In addition,  the Registrant
expended $6 million for the acquisition of nuclear fuel. The Registrant received
Board of  Directors  approval  on April  25,  2000 to spend  approximately  $160
million  on  capital  expenditures  relating  to the  replacement  of four steam
generators  at its  Callaway  Nuclear  Plant.  Installation  is  scheduled to be
completed in 2005. The impact on anticipated 2000 capital  expenditures  will be
insignificant.

Cash flows used in  financing  activities  totaled  $171  million  for the three
months  ended  March 31,  2000,  compared  to $64  million  during the same 1999
period. The Registrant's  principal financing activities for the period included
redemption  of long-term  debt and the payment of  dividends.  Proceeds from the
issuance of certain long-term debt have been set aside in an environmental  bond
redemption  fund to be used to retire  existing  long-term  indebtedness  in the
second quarter.

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 $1  billion 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 March 31,
2000, the Registrant had committed bank lines of credit aggregating $150 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 March 31, 2000, the Registrant
had no outstanding short-term borrowings.

The  Registrant  also has a bank  credit  agreement  due 2002 which  permits the
borrowing of up to $300 million on a long-term  basis,  all of which was unused,
and $247 was available at March 31, 2000. In addition,  the  Registrant  has the
ability to borrow up to  approximately  $530 million  from Ameren or  AmerenCIPS
through  a  regulated  money  pool  agreement.  The  regulated  money  pool  was
established  to coordinate and provide for certain  short-term  cash and working
capital  requirements  and is administered by Ameren Services  Company,  another
subsidiary  of Ameren.  Interest  is  calculated  at varying  rates of  interest
depending on the  composition  of internal and external  funds in the  regulated
money  pool.  As of March 31,  2000,  $333  million  was  available  through the
regulated money pool.

Additionally,  the  Registrant  has a  lease  agreement  that  provides  for the
financing of nuclear fuel. At March 31, 2000,  the maximum  amount that could be
financed under the agreement was $120 million. Cash used in financing activities
for the three months ended March 31, 2000, included  redemptions under the lease
for nuclear fuel of $2 million,  offset by $1 million of issuances. At March 31,
2000, $116 million was financed under the lease.

The Registrant,  in the ordinary course of business,  explores  opportunities to
reduce its cost in order to remain  competitive in the marketplace.  Areas where
the Registrant  focuses its review include,  but are not limited to, labor costs
and fuel supply costs. In the labor area, the Registrant has reached  agreements
with some of the Registrant's  collective  bargaining units which will permit it
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.  In the fuel supply area, the Registrant
explores  alternatives  to  effectively  manage its overall  fuel  costs.  These
alternatives include diversifying

                                      -4-

<PAGE>

fuel sources for use at the Registrant's fossil plants, as well as restructuring
or terminating existing contracts with suppliers.

Certain  of  these  cost  reduction  alternatives  could  result  in  additional
investments  being  made at the  Registrant's  power  plants in order to utilize
different  types of coal,  or could  require  nonrecurring  payments of employee
separation  benefits or  nonrecurring  payments to  restructure  or terminate an
existing fuel  contract  with a supplier.  Management is unable to predict which
(if any),  and to what  extent,  these  alternatives  to reduce its overall cost
structure  will be executed.  Management  is unable to  determine  the impact of
these  actions  on  the  Registrant's  future  financial  position,  results  of
operations or liquidity.


RATE MATTERS

In February  2000,  the  Registrant  filed a request  with the  Missouri  Public
Service Commission (MoPSC) to increase rates  approximately $12 million annually
for  natural  gas  service  in the  Missouri  jurisdiction.  The MoPSC has until
January 2001 to render a decision.

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


ELECTRIC INDUSTRY RESTRUCTURING

Certain states are considering  proposals or have adopted  legislation that will
promote  competition  at the retail  level.  In December  1997,  the Governor of
Illinois signed the Electric Service Customer Choice and Rate Relief Law of 1997
(the Illinois Law)  providing for electric  utility  restructuring  in Illinois.
This  legislation  introduces  competition into the supply of electric energy in
Illinois.

The Illinois Law, among other things,  requires the  phasing-in  through 2002 of
retail direct access, which allows customers to choose their electric generation
supplier.  The phase-in of retail direct  access began on October 1, 1999,  with
large  commercial and industrial  customers  principally  comprising the initial
group.  The  customers in this group  represent  approximately  6 percent of the
Registrant's  total  sales.  As of March 31, 2000,  the impact of retail  direct
access  on the  Registrant's  financial  condition,  results  of  operations  or
liquidity was immaterial.  Retail direct access will be offered to the remaining
commercial  and  industrial  customers on December 31, 2000,  and to residential
customers on May 1, 2002.


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  business,  legal,  operational and credit risk and are not
represented in the following analysis.

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

If interest rates increase one percentage point in 2001 as compared to 2000, the
Registrant's interest expense would increase by approximately $6 million and net
income  would  decrease  by  approximately  $4  million.  This  amount  has been
determined using the assumptions that the Registrant's outstanding variable rate
debt as of March 31, 2000, continued to be outstanding throughout 2001, and that
the average interest rates for these instruments  increased one percentage point
over 2000.  The model does not  consider  the  effects of the  reduced  level of
overall economic activity that would exist in such an environment.  In the event
of a significant change in interest rates, management

                                      -5-

<PAGE>

would likely take actions to further  mitigate its exposure to this market risk.
However,  due to the uncertainty of the specific actions that would be taken and
their  possible  effects,  the  sensitivity  analysis  assumes  no change in the
Registrant's financial structure.

Commodity Price Risk
The  Registrant  is exposed to changes in market prices for natural gas and fuel
and  electricity.   With  regard  to  its  natural  gas  utility  business,  the
Registrant's  exposure to changing  market prices is in large part  mitigated by
the fact that Registrant has Purchased Gas Adjustment  Clauses (PGA) in place in
both its Missouri and Illinois  jurisdictions.  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 and nuclear fuel to manage its exposure
to fuel prices. With regard to the Registrant's exposure to commodity price risk
for  purchased  power and excess  electricity  sales,  Ameren has  established a
subsidiary,  AmerenEnergy,  Inc.,  (AmerenEnergy)  whose primary  responsibility
includes  managing  market risks  associated with the changing market prices for
electricity purchased and sold on behalf of the Registrant.

AmerenEnergy  utilizes  several  techniques  to  mitigate  its  market  risk for
electricity,  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,  futures  contracts,  and
option  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 March 31, 2000, the fair value of derivative financial instruments exposed
to commodity price risk was immaterial.

Equity Price Risk

The  Registrant  maintains  trust funds,  as required by the Nuclear  Regulatory
Commission  and  Missouri  and Illinois  state laws,  to fund  certain  costs of
nuclear  decommissioning.  As of March  31,  2000,  these  funds  were  invested
primarily in domestic equity securities,  fixed-rate,  fixed-income  securities,
and cash  and  cash  equivalents.  By  maintaining  a  portfolio  that  includes
long-term equity investments,  the Registrant is seeking to maximize the returns
to be  utilized  to fund  nuclear  decommissioning  costs.  However,  the equity
securities  included  in  the  Registrant's   portfolio  are  exposed  to  price
fluctuations in equity markets, and the fixed-rate,  fixed-income securities are
exposed to changes in interest  rates.  The  Registrant  actively  monitors  its
portfolio by benchmarking  the  performance of its  investments  against certain
indices and by  maintaining,  and  periodically  reviewing,  established  target
allocation  percentages  of the  assets  of its  trusts  to  various  investment
options. The Registrant's  exposure to equity price market risk is in large part
mitigated due to the fact that the  Registrant  is currently  allowed to recover
its decommissioning costs in its rates.


SAFE HARBOR STATEMENT

Statements made in this Form 10-Q which are not based on historical  facts,  are
"forward-looking"  and, accordingly,  involve risks and uncertainties that could
cause actual results to differ  materially from those  discussed.  Although such
"forward-looking"  statements  have  been  made in good  faith  and are based on
reasonable assumptions,  there is no assurance that the expected results will be
achieved.  These statements include (without limitation) statements as to future
expectations,   beliefs,  plans,  strategies,  objectives,  events,  conditions,
financial  performance  and the Year 2000 Issue.  In  connection  with the "Safe
Harbor" provisions of the Private Securities  Litigation Reform Act of 1995, the
Registrant is providing this cautionary  statement to identify important factors
that could cause actual results to differ materially from those anticipated. The
following factors,  in addition to those discussed  elsewhere in this report and
in the Annual  Report on Form 10-K for the fiscal year ended  December 31, 1999,
and in subsequent  securities filings,  could cause results to differ materially
from management expectations as suggested by such "forward-looking"  statements:
the  effects  of  regulatory  actions;  changes  in laws and other  governmental
actions;  the impact on the  Registrant  of current  regulations  related to the
phasing-in of the  opportunity for some customers to choose  alternative  energy
suppliers in Illinois;  the effects of increased  competition  in the future due
to, among other

                                      -6-

<PAGE>

things, deregulation of certain aspects of the Registrant's business at both the
State and Federal  levels;  future market  prices for fuel and purchased  power,
electricity,  and  natural  gas,  including  the use of  financial  instruments;
average rates for electricity in the Midwest;  business and economic conditions;
interest rates;  weather  conditions;  fuel prices and availability;  generation
plant performance;  the impact of current environmental regulations on utilities
and generating  companies and the expectation  that more stringent  requirements
will be introduced over time, which could potentially have a negative  financial
effect; monetary and fiscal policies;  future wages and employee benefits costs;
and legal and administrative proceedings.

                                      -7-

<PAGE>

<TABLE>
<CAPTION>

                             UNION ELECTRIC COMPANY
                                  BALANCE SHEET
                                    UNAUDITED
                                    ---------
                      (Thousands of Dollars, Except Shares)

                                                                  March 31,   December 31,
ASSETS                                                              2000         1999
------                                                           ----------   ----------
<S>                                                             <C>          <C>
Property and plant, at original cost:
   Electric                                                      $9,271,152   $9,210,122
   Gas                                                              227,832      223,789
   Other                                                             37,156       37,156
                                                                 ----------   ----------
                                                                  9,536,140    9,471,067
   Less accumulated depreciation and amortization                 4,380,588    4,320,910
                                                                 ----------   ----------
                                                                  5,155,552    5,150,157
Construction work in progress:
   Nuclear fuel in process                                           95,294       88,830
   Other                                                            114,257       92,833
                                                                 ----------   ----------
         Total property and plant, net                            5,365,103    5,331,820
                                                                 ----------   ----------
Investments and other assets:
   Nuclear decommissioning trust fund                               193,438      186,760
   Other                                                             61,264       59,748
                                                                 ----------   ----------
         Total investments and other assets                         254,702      246,508
                                                                 ----------   ----------
Current assets:
   Cash and cash equivalents                                          6,415      117,308
   Environmental bond redemption fund                               186,500         --
   Accounts receivable - trade (less allowance for doubtful
         accounts of $5,598 and $5,308, respectively)               135,220      151,399
   Unbilled revenue                                                  47,853       78,213
   Other accounts and notes receivable                               21,645       19,803
   Intercompany notes receivable                                    142,460      165,700
   Materials and supplies, at average cost -
      Fossil fuel                                                    57,872       65,292
      Other                                                          79,572       90,921
   Other                                                             17,638       19,205
                                                                 ----------   ----------
         Total current assets                                       695,175      707,841
                                                                 ----------   ----------
Regulatory assets:
   Deferred income taxes                                            600,604      600,604
   Other                                                            155,350      156,789
                                                                 ----------   ----------
         Total regulatory assets                                    755,954      757,393
                                                                 ----------   ----------
Total Assets                                                     $7,070,934   $7,043,562
                                                                 ==========   ==========

CAPITAL AND LIABILITIES
Capitalization:
   Common stock, $5 par value, 150,000,000 shares authorized -
     102,123,834 shares outstanding                              $  510,619   $  510,619
   Other paid-in capital, principally premium on
     common stock                                                   701,896      701,896
   Retained earnings                                              1,189,123    1,221,167
                                                                 ----------   ----------
         Total common stockholder's equity                        2,401,638    2,433,682
   Preferred stock not subject to mandatory redemption              155,197      155,197
   Long-term debt                                                 1,782,513    1,882,601
                                                                 ----------   ----------
         Total capitalization                                     4,339,348    4,471,480
                                                                 ----------   ----------
Current liabilities:
   Current maturity of long-term debt                               199,291       11,423
   Accounts and wages payable                                       130,416      234,845
   Accumulated deferred income taxes                                 48,139       48,139
   Taxes accrued                                                    171,731      119,699
   Other                                                            220,130      208,373
                                                                 ----------   ----------
         Total current liabilities                                  769,707      622,479
                                                                 ----------   ----------
Accumulated deferred income taxes                                 1,246,741    1,248,721
Accumulated deferred investment tax credits                         137,145      138,665
Regulatory liability                                                153,246      154,399
Other deferred credits and liabilities                              424,747      407,818
                                                                 ----------   ----------
Total Capital and Liabilities                                    $7,070,934   $7,043,562
                                                                 ==========   ==========

</TABLE>

See Notes to Financial Statements.

                                      -8-

<PAGE>

<TABLE>
<CAPTION>

                             UNION ELECTRIC COMPANY
                               STATEMENT OF INCOME
                                    UNAUDITED
                                    ---------
                             (Thousands of Dollars)


                                                                  Three Months Ended          Twelve Months Ended
                                                                       March 31,                   March 31,
                                                                  ------------------          --------------------
                                                                  2000          1999          2000            1999
                                                                  ----          ----          ----            ----

 OPERATING REVENUES:
<S>                                                        <C>            <C>            <C>            <C>
    Electric                                                $   519,113    $   461,134    $ 2,492,996    $ 2,315,343
    Gas                                                          42,077         44,917         89,138         93,998
    Other                                                          --               20            151            216
                                                            -----------    -----------    -----------    -----------
       Total operating revenues                                 561,190        506,071      2,582,285      2,409,557

 OPERATING EXPENSES:
    Operations
       Fuel and purchased power                                 172,438        120,575        708,397        539,247
       Gas                                                       22,599         21,800         55,268         51,317
       Other                                                    104,725         97,924        441,257        459,802
                                                            -----------    -----------    -----------    -----------
                                                                299,762        240,299      1,204,922      1,050,366
    Maintenance                                                  52,260         50,623        248,772        224,573
    Depreciation and amortization                                67,066         65,405        257,733        260,671
    Income taxes                                                 28,612         31,255        228,048        224,208
    Other taxes                                                  47,715         49,602        202,654        214,789
                                                            -----------    -----------    -----------    -----------
       Total operating expenses                                 495,415        437,184      2,142,129      1,974,607

 OPERATING INCOME                                                65,775         68,887        440,156        434,950

 OTHER INCOME AND (DEDUCTIONS):
    Allowance for equity funds used during
       construction                                               1,229          2,669          5,730          6,637
    Miscellaneous, net                                            2,879          1,328         13,199         12,751
                                                            -----------    -----------    -----------    -----------
       Total other income and (deductions)                        4,108          3,997         18,929         19,388

 INCOME BEFORE INTEREST CHARGES                                  69,883         72,884        459,085        454,338

 INTEREST CHARGES :
    Interest                                                     32,466         30,923        121,521        126,710
    Allowance for borrowed funds used during construction        (1,819)        (1,782)        (7,181)        (5,883)
                                                             -----------    -----------    -----------    -----------
 Net interest charges                                            30,647         29,141        114,340        120,827
                                                            -----------    -----------    -----------    -----------
 NET INCOME                                                      39,236         43,743        344,745        333,511

 PREFERRED STOCK DIVIDENDS                                        2,204          2,204          8,817          8,817
                                                            -----------    -----------    -----------    -----------
NET INCOME AFTER PREFERRED
                STOCK DIVIDENDS                             $    37,032    $    41,539    $   335,928    $   324,694
                                                            ===========    ===========    ===========    ===========

</TABLE>

See Notes to Financial Statements.

                                      -9-

<PAGE>

<TABLE>
<CAPTION>


                             UNION ELECTRIC COMPANY
                             STATEMENT OF CASH FLOWS
                                    UNAUDITED
                                    ---------
                             (Thousands of Dollars)


                                                           Three Months Ended
                                                                March 31,
                                                           ------------------
                                                           2000         1999
                                                           ----         ----
Cash Flows From Operating:
<S>                                                   <C>          <C>
   Net income                                          $  39,236    $  43,743
   Adjustments to reconcile net income to net cash
      provided by operating activities:
        Depreciation and amortization                     64,077       63,071
        Amortization of nuclear fuel                       9,075       10,416
        Allowance for funds used during construction      (3,048)      (4,451)
        Deferred income taxes, net                        (3,284)      (4,507)
        Deferred investment tax credits, net              (1,520)      (1,386)
        Changes in assets and liabilities:
           Receivables, net                               44,697       (4,381)
           Materials and supplies                         18,769       (3,584)
           Accounts and wages payable                   (104,429)    (103,745)
           Taxes accrued                                  52,032       60,502
           Other, net                                     25,030       54,108
                                                       ---------    ---------
Net cash provided by operating activities                140,635      109,786

Cash Flows From Investing:
   Construction expenditures                            (100,124)     (49,473)
   Allowance for funds used during construction            3,048        4,451
   Nuclear fuel expenditures                              (6,228)      (2,381)
   Intercompany notes receivable                          23,240         --
                                                       ---------    ---------
Net cash used in investing activities                    (80,064)     (47,403)

Cash Flows From Financing:
   Dividends on common stock                             (69,076)     (61,581)
   Dividends on preferred stock                           (2,204)      (2,204)
   Environmental bond redemption fund                   (186,500)        --
      Redemptions -
         Nuclear fuel lease                               (1,818)      (3,635)
         Long-term debt                                  (99,722)        --
      Issuances -
         Nuclear fuel lease                                1,356        3,617
         Long-term debt                                  186,500         --
                                                       ---------    ---------
Net cash used in financing activities                   (171,464)     (63,803)

Net change in cash and cash equivalents                 (110,893)      (1,420)
Cash and cash equivalents at beginning of year           117,308       47,337
                                                       ---------    ---------
Cash and cash equivalents at end of period             $   6,415    $  45,917
                                                       =========    =========

Cash paid during the periods:
   Interest (net of amount capitalized)                $  22,890    $  20,217
   Income taxes, net                                   $    (179)   $  (2,633)

</TABLE>

See Notes to Financial Statements.

                                      -10-

<PAGE>

UNION ELECTRIC COMPANY
NOTES TO FINANCIAL STATEMENTS (UNAUDITED)
March 31, 2000

Note 1 - Union Electric Company  (AmerenUE or the Registrant) is a subsidiary of
Ameren  Corporation  (Ameren),  which  is the  parent  company  of  two  utility
operating companies,  the Registrant and Central Illinois Public Service Company
(AmerenCIPS).  Ameren is a registered  holding  company under the Public Utility
Holding  Company Act of 1935 (PUHCA)  formed in December 1997 upon the merger of
AmerenUE and CIPSCO Incorporated (the Merger).  Both Ameren and its subsidiaries
are subject to the regulatory  provisions of the PUHCA. The operating  companies
are engaged principally in the generation,  transmission,  distribution and sale
of electric energy and the purchase,  distribution,  transportation  and sale of
natural  gas in the  states  of  Missouri  and  Illinois.  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
1.1 million  electric and 124,000 gas customers in a 24,500  square-mile area of
Missouri and Illinois, including Metropolitan St. Louis.

The Registrant also has a 40 percent  interest in Electric  Energy,  Inc. (EEI),
which is  accounted  for under the  equity  method of  accounting.  EEI owns and
operates an  electric  generating  and  transmission  facility in Illinois  that
supplies  electric  power  primarily to a uranium  enrichment  plant  located in
Paducah, Kentucky.

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

Note 3 - In the opinion of the Registrant the interim financial statements filed
as part of this Form 10-Q  reflect all  adjustments,  consisting  only of normal
recurring  adjustments,  necessary  for a fair  statement of the results for the
periods presented. 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 March 31, 2000 and 1999, are not necessarily  indicative of trends for any
three-month or 12-month period.

Note 5 - - In July 1995, the Missouri Public Service Commission (MoPSC) approved
an agreement  establishing  contractual  obligations  involving the Registrant's
Missouri  retail  electric  rates.   Included  was  a  three-year   experimental
alternative  regulation  plan  (the  Original  Plan)  that ran from July 1, 1995
through June 30, 1998,  which provided that earnings in those years in excess of
a 12.61  percent  regulatory  return on equity (ROE) be shared  equally  between
customers and  stockholders,  and earnings above a 14 percent ROE be credited to
customers. The formula for computing the credit used twelve-month results ending
June 30, rather than calendar year earnings.

The MoPSC staff proposed  adjustments  to the  Registrant's  estimated  customer
credit for the final year of the Original  Plan ended June 30, 1998,  which were
the  subject of  regulatory  proceedings  before the MoPSC in 1999.  In December
1999,  the MoPSC issued a Report and Order  (Order)  concerning  these  proposed
adjustments.  Based on the provisions of that Order, the Registrant  revised its
estimated final year credit to $31 million.  Subsequently, in December 1999, the
Registrant  filed a request for  rehearing  of the Order with the MoPSC,  asking
that  it  reconsider  its  decision  to  adopt  certain  of  the  MoPSC  staff's
adjustments.  The  request  was denied by the MoPSC and in  February  2000,  the
Registrant  filed a Petition  for Writ of Review with the Circuit  Court of Cole
County,  Missouri,  requesting that the Order be reversed.

                                      -11-

<PAGE>

The appeal is pending and the ultimate  outcome can not be  predicted;  however,
the final decision is not expected to materially impact the financial condition,
results of  operations  or  liquidity of the  Registrant.  A partial stay of the
Order was granted by the Court pending the appeal.

A new three-year  experimental  alternative  regulation  plan (the New Plan) was
included in the joint  agreement  authorized  by the MoPSC in its February  1997
order  approving the Merger.  Like the Original Plan, the New Plan requires that
earnings  over a 12.61  percent  ROE up to a 14  percent  ROE be shared  equally
between  customers and  stockholders.  The New Plan also returns to customers 90
percent of all earnings above a 14 percent ROE up to a 16 percent ROE.  Earnings
above a 16 percent ROE are  credited  entirely to  customers.  The New Plan runs
from July 1, 1998 through June 30, 2001. During the three months ended March 31,
2000,  the  Registrant  recorded an  estimated  $10 million  credit (4 cents per
share) for the plan year ending June 30, 2000 that the Registrant expects to pay
its  Missouri  electric  customers.  In total,  the  Registrant  has recorded an
estimated  credit of $30  million as of March 31,  2000 for the plan year ending
June 30, 2000,  compared to an estimated  $20 million  credit  recorded over the
same period last year.  These credits were  reflected as a reduction in electric
revenues.  The final  amount of the  credit  will  depend  on  several  factors,
including  the  Registrant's  earnings for 12 months ended June 30, 2000.  As of
March 31, 2000,  the  Registrant  has also  reflected  an estimated  $25 million
credit it expects to pay its Missouri electric customers for the plan year ended
June 30, 1999.  The  Registrant's  proposed  credit is still under review by the
MoPSC staff and the Office of the Public Counsel.

The joint  agreement  approved by the MoPSC in its February 1997 Order approving
the Merger also provided for a Missouri  electric rate decrease,  retroactive to
September  1, 1998,  based on the  weather-adjusted  average  annual  credits to
customers  under the Original  Plan. The rate decrease was impacted by the Order
issued by the MoPSC in December 1999  relating to the  estimated  credit for the
third year of the Original Plan and a settlement reached between the Registrant,
the  MoPSC  staff  and  other  parties   relating  to  the  calculation  of  the
weather-adjusted  credits. Based on those results, the Registrant estimates that
its Missouri  electric rate decrease will be $17 million on an annualized basis.
This  estimate  is subject to the final  outcome of the  above-referenced  court
appeal of the Order.

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  $19 million
and $15  million,  respectively,  as of March 31, 2000 and  December  31,  1999.
Intercompany   payables   included  in  accounts  and  wages   payable   totaled
approximately  $21 million and $25 million,  respectively,  as of March 31, 2000
and December 31, 1999.

Also, the Registrant has the ability to borrow up to approximately  $530 million
from  Ameren or  AmerenCIPS  through  a  regulated  money  pool  agreement.  The
regulated  money pool was  established  to  coordinate  and  provide for certain
short-term cash and working capital  requirements  and is administered by Ameren
Services Company.  Interest is calculated at varying rates of interest depending
on the  composition of internal and external funds in the regulated  money pool.
At March 31, 2000, the Registrant had  outstanding  intercompany  receivables of
$142 million and $333 million available through the regulated money pool.

                                      -12-

<PAGE>

                           PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS
        -----------------

     Reference  is  made  to  "Liquidity  and  Capital   Resources"  in  Item 7.
Management's  Discussion  and  Analysis of  Financial  Condition  and Results of
Operations and Note 12 - Commitments and Contingencies in the Notes to Financial
Statements in the  Registrant's  Form 10-K for the year ended December 31, 1999,
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 1999,  the United  States  Court of Appeals for the
District  of  Columbia   Circuit  remanded  the  ambient  air  quality  standard
regulations  to the EPA for  reconsideration.  In January and February 2000, the
parties to the  litigation  filed  petitions for review before the United States
Supreme Court.  The Supreme Court has not decided whether to accept the case for
review. 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.


ITEM 4. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS
        --------------------------------------------------

     At the annual meeting of  stockholders  of the Registrant held on April 25,
2000,  the  following  matter was  presented  to the  meeting for a vote and the
results of such voting are as follows:

     Item (1) Election of Directors.

                                                                      Non-Voted
          Name                             For            Withheld     Brokers
          ----                             ---            --------    ---------

     Paul A. Agathen.............      104,080,301         18,457         0
     Warner L. Baxter............      104,078,764         19,815         0
     Donald E. Brandt............      104,079,864         18,807         0
     Charles W. Mueller..........      104,079,807         18,864         0
     Gary L. Rainwater...........      104,079,157         19,514         0


ITEM 6. EXHIBIT 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 March 31, 2000.

          Exhibit 27 - Financial Data Schedule.

          The  following  instrument  defining  the rights of holders of certain
          unregistered  long-term  debt of AmerenUE  has not been filed with the
          Securities and Exchange Commission but will be furnished upon request.



          1.   Loan Agreement dated as of March 1, 2000 between AmerenUE and the
               State Environmental Improvement and Energy Resources Authority of
               the State of  Missouri  (EIERA) in  connection  with the  EIERA's
               $186,500,000  Environmental  Improvement  Revenue Refunding Bonds
               (AmerenUE Project) ($63,500,000 Series 2000A,  $63,000,000 Series
               2000B, and $60,000,000 Series 2000C) due March 1, 2035.


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

                                      -13-

<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.

                                           UNION ELECTRIC COMPANY
                                               (Registrant)


                                           By  /S/ Donald E. Brandt
                                              ----------------------
                                                   Donald E. Brandt
                                                Senior Vice President
                                           Finance and Corporate Services
                                            (Principal Financial Officer)


Date: May 15, 2000

                                      -14-