UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM 10-Q/A

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

                  For the Quarterly Period Ended March 31, 2003
                                       OR

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

<TABLE>
<CAPTION>
     Commission                 Name of Registrant; State of Incorporation;                  IRS Employer
     File Number                Address of Principal Executive Offices; and                  Identification
                                Telephone Number                                             Number
---------------------      ---------------------------------------------------------    ------------------------
  <C>                                                                                     <C>
     1-16169                    EXELON CORPORATION                                           23-2990190
                                (a Pennsylvania corporation)
                                10 South Dearborn Street - 37th Floor
                                P.O. Box 805379
                                Chicago, Illinois 60680-5379
                                (312) 394-7398

     1-1839                     COMMONWEALTH EDISON COMPANY                                  36-0938600
                                (an Illinois corporation)
                                10 South Dearborn Street - 37th Floor
                                P.O. Box 805379
                                Chicago, Illinois 60680-5379
                                (312) 394-4321

     1-1401                     PECO ENERGY COMPANY                                          23-0970240
                                (a Pennsylvania corporation)
                                P.O. Box 8699 2301 Market Street
                                Philadelphia, Pennsylvania 19101-8699
                                (215) 841-4000

     333-85496                  EXELON GENERATION COMPANY, LLC                               23-3064219
                                (a Pennsylvania limited liability company)
                                300 Exelon Way
                                Kennett Square, Pennsylvania 19348
                                (610) 765-6900
</TABLE>

     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 [_].

     The number of shares outstanding of each registrant's common stock as of
March 31, 2003 was:

     Exelon Corporation Common Stock, without par value             324,234,521
     Commonwealth Edison Company Common Stock, $12.50 par value     127,016,427
     PECO Energy Company Common Stock, without par value            170,478,507
     Exelon Generation Company, LLC                              not applicable

     Indicate by check mark whether the registrant is an accelerated filer (as
defined in Rule 12b-2 of the Act). Exelon Corporation Yes [X] No [ ]
Commonwealth Edison Company, PECO Energy Company and Exelon Generation Company,
LLC Yes [ ] No [X].

<PAGE>



                                TABLE OF CONTENTS


                                                                  Page No.
      FILING FORMAT                                                      3
      EXPLANATORY NOTE                                                   3

      PART I.   FINANCIAL INFORMATION                                    4
      ITEM 4.   CONTROLS AND PROCEDURES                                  4
      PART II.  OTHER INFORMATION                                        7
      ITEM 6.   EXHIBITS AND REPORTS ON FORM 8-K                         7

      SIGNATURES                                                        10






















                                       2
<PAGE>

     FILING FORMAT
              This combined Form 10-Q/A is being filed separately by Exelon
     Corporation (Exelon), Commonwealth Edison Company (ComEd), PECO Energy
     Company (PECO) and Exelon Generation Company, LLC (Generation)
     (Registrants). Information contained herein relating to any individual
     registrant has been filed by such registrant on its own behalf. No
     registrant makes any representation as to information relating to any other
     registrant.

     EXPLANATORY NOTE
              Exelon, ComEd, PECO and Generation are filing this amendment on
     Form 10-Q/A in response to comments received from the staff of the
     Securities and Exchange Commission (SEC) in connection with its review of
     Exelon's Registration Statement on Form S-3 (File No. 333-108546), which
     incorporates this quarterly report by reference.

              This amendment makes changes to Part I, Item 4. Controls and
     Procedures to confirm that each Registrant's disclosure controls and
     procedures are effective and to clarify that each Registrant's access and
     ability to apply its disclosure controls and procedures to entities that it
     does not control or manage are more limited than subsidiaries that it
     controls and manages.

              Unless otherwise stated, all information contained in this
     amendment is as of May 2, 2003, the filing date of our original Quarterly
     Report on Form 10-Q for the quarter ended March 31, 2003.





                                       3
<PAGE>

     PART I.          FINANCIAL INFORMATION
     ITEM 4.          CONTROLS AND PROCEDURES

     Exelon
              During the first quarter of 2003, Exelon's management, including
     the principal executive officer and principal financial officer, evaluated
     Exelon's disclosure controls and procedures related to the recording,
     processing, summarization and reporting of information in Exelon's periodic
     reports that it files with the SEC. These disclosure controls and
     procedures have been designed to ensure that (a) material information
     relating to Exelon, including its consolidated subsidiaries, is made known
     to Exelon's management, including these officers, by other employees of
     Exelon and its subsidiaries, and (b) this information is recorded,
     processed, summarized, evaluated and reported, as applicable, within the
     time periods specified in the SEC's rules and forms. Due to the inherent
     limitations of control systems, not all misstatements may be detected.
     These inherent limitations include the realities that judgments in
     decision-making can be faulty and that breakdowns can occur because of
     simple error or mistake. Additionally, controls could be circumvented by
     the individual acts of some persons or by collusion of two or more people.
     Exelon's controls and procedures can only provide reasonable, not absolute,
     assurance that the above objectives have been met. Exelon does not control
     or manage certain of its unconsolidated entities and thus its access and
     ability to apply its disclosure controls and procedures to entities that it
     does not control or manage are more limited than is the case for the
     subsidiaries it controls and manages.

              Accordingly, as of March 31, 2003, these officers (principal
     executive officer and principal financial officer) concluded that Exelon's
     disclosure controls and procedures were effective to accomplish their
     objectives. Exelon continually strives to improve its disclosure controls
     and procedures to enhance the quality of its financial reporting and to
     maintain dynamic systems that change as conditions warrant.

     ComEd
              During the first quarter of 2003, ComEd's management, including
     the principal executive officer and principal financial officer, evaluated
     ComEd's disclosure controls and procedures related to the recording,
     processing, summarization and reporting of information in ComEd's periodic
     reports that it files with the SEC. These disclosure controls and
     procedures have been designed to ensure that (a) material information
     relating to ComEd, including its consolidated subsidiaries, is made known
     to ComEd's management, including these officers, by other employees of
     ComEd and its subsidiaries, and (b) this information is recorded,
     processed, summarized, evaluated and reported, as applicable, within the
     time periods specified in the SEC's rules and forms. Due to the inherent
     limitations of control systems, not all misstatements may be detected.
     These inherent limitations include the realities that judgments in
     decision-making can be faulty and that breakdowns can occur because of
     simple error or mistake. Additionally, controls could be circumvented by
     the individual acts of some persons or by collusion of two or more people.
     ComEd's controls and procedures can only provide reasonable, not absolute,
     assurance that the above objectives have been met. ComEd does not control
     or manage certain of its unconsolidated entities and thus its access and





                                       4
<PAGE>

     ability to apply its disclosure controls and procedures to entities that it
     does not control or manage are more limited than is the case for the
     subsidiaries it controls and manages.

              Accordingly, as of March 31, 2003, these officers (principal
     executive officer and principal financial officer) concluded that ComEd's
     disclosure controls and procedures were effective to accomplish their
     objectives. ComEd continually strives to improve its disclosure controls
     and procedures to enhance the quality of its financial reporting and to
     maintain dynamic systems that change as conditions warrant.

     PECO
              During the first quarter of 2003, PECO's management, including the
     principal executive officer and principal financial officer, evaluated
     PECO's disclosure controls and procedures related to the recording,
     processing, summarization and reporting of information in PECO's periodic
     reports that it files with the SEC. These disclosure controls and
     procedures have been designed to ensure that (a) material information
     relating to PECO, including its consolidated subsidiaries, is made known to
     PECO's management, including these officers, by other employees of PECO and
     its subsidiaries, and (b) this information is recorded, processed,
     summarized, evaluated and reported, as applicable, within the time periods
     specified in the SEC's rules and forms. Due to the inherent limitations of
     control systems, not all misstatements may be detected. These inherent
     limitations include the realities that judgments in decision-making can be
     faulty and that breakdowns can occur because of simple error or mistake.
     Additionally, controls could be circumvented by the individual acts of some
     persons or by collusion of two or more people. PECO's controls and
     procedures can only provide reasonable, not absolute, assurance that the
     above objectives have been met. PECO does not control or manage certain of
     its unconsolidated entities and thus its access and ability to apply its
     disclosure controls and procedures to entities that it does not control or
     manage are more limited than is the case for the subsidiaries it controls
     and manages.

              Accordingly, as of March 31, 2003, these officers (principal
     executive officer and principal financial officer) concluded that PECO's
     disclosure controls and procedures were effective to accomplish their
     objectives. PECO continually strives to improve its disclosure controls and
     procedures to enhance the quality of its financial reporting and to
     maintain dynamic systems that change as conditions warrant.

     Generation
              During the first quarter of 2003, Generation's management,
     including the principal executive officer and principal financial officer,
     evaluated Generation's disclosure controls and procedures related to the
     recording, processing, summarization and reporting of information in
     Generation's periodic reports that it files with the SEC. These disclosure
     controls and procedures have been designed to ensure that (a) material
     information relating to Generation, including its consolidated
     subsidiaries, is made known to Generation's management, including these
     officers, by other employees of Generation and its subsidiaries, and (b)
     this information is recorded, processed, summarized, evaluated and
     reported, as applicable, within the time periods specified in the SEC's
     rules and forms. Due to the inherent limitations of control systems, not
     all misstatements may be detected. These inherent limitations include the
     realities that judgments in decision-making can be faulty and that
     breakdowns can occur because of simple error or mistake. Additionally,





                                       5
<PAGE>

     controls could be circumvented by the individual acts of some persons or by
     collusion of two or more people. Generation's controls and procedures can
     only provide reasonable, not absolute, assurance that the above objectives
     have been met. Generation does not control or manage certain of its
     unconsolidated entities and thus its access and ability to apply its
     disclosure controls and procedures to entities that it does not control or
     manage are more limited than is the case for the subsidiaries it controls
     and manages.

              Accordingly, as of March 31, 2003, these officers (principal
     executive officer and principal financial officer) concluded that
     Generation's disclosure controls and procedures were effective to
     accomplish their objectives. Generation continually strives to improve its
     disclosure controls and procedures to enhance the quality of its financial
     reporting and to maintain dynamic systems that change as conditions
     warrant.






                                       6
<PAGE>


     PART II - OTHER INFORMATION
     ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K
     (a) Exhibits:

       4-1 -      One Hundredth Supplemental Indenture dated as of April 15,
                  2003 to PECO Energy Company's First and Refunding Mortgage.*

        Certifications   Pursuant  to  Rule   13a-14(a)  and  15d-14(a)  of  the
        Securities  and Exchange Act of 1934 as to the Quarterly  Report on Form
        10-Q/A  for the  quarterly  period  ended  March 31,  2003  filed by the
        following officers for the following companies:
       -------------------------------------------------------------------------
       31-1  -    Filed by John W. Rowe for Exelon Corporation
       31-2  -    Filed by Robert S. Shapard for Exelon Corporation
       31-3  -    Filed by Michael B. Bemis for Commonwealth Edison Company
       31-4  -    Filed by J. Barry Mitchell for Commonwealth Edison Company
       31-5  -    Filed by Michael B. Bemis for PECO Energy Company
       31-6  -    Filed by J. Barry Mitchell for PECO Energy Company
       31-7  -    Filed by Oliver D. Kingsley Jr. for Exelon Generation Company,
                  LLC
       31-8  -    Filed by J. Barry Mitchell for Exelon Generation Company, LLC
       -------------------------------------------------------------------------

       Certifications Pursuant to Section 1350 of Chapter 63 of Title 18 United
       States Code (Sarbanes - Oxley Act of 2002) as to the Quarterly Report on
       Form 10-Q for the quarterly period ended March 31, 2003 filed by the
       following officers for the following companies:*
       -------------------------------------------------------------------------

       99-1 -     Filed by John W. Rowe for Exelon Corporation
       99-2 -     Filed by Robert S. Shapard for Exelon Corporation
       99-3 -     Filed by Pamela B. Strobel for Commonwealth Edison Company
       99-4 -     Filed by Robert S. Shapard for Commonwealth Edison Company
       99-5 -     Filed by Pamela B. Strobel for PECO Energy Company
       99-6 -     Filed by Robert S. Shapard for PECO Energy Company
       99-7 -     Filed by Oliver D. Kingsley Jr. for Exelon Generation Company,
                  LLC
       99-8 -     Filed by Robert S. Shapard for Exelon Generation Company, LLC
       -------------------------------------------------------------------------

     * Exhibits were filed with the Form 10-Q for the quarterly period ended
     March 31, 2003 filed on May 2, 2003 (File No. 1-16169, March 31, 2003 Form
     10-Q, Exhibits 4-1 through 99-8).

     (b) Reports on Form 8-K:

                  Exelon, ComEd, PECO and/or Generation filed Current Reports on
         Form 8-K during the three months ended March 31, 2003 regarding the
         following items:

<TABLE>
<CAPTION>
         Date of Earliest
         Event Reported             Description of Item Reported
------------------------------------------------------------------------------------------------------------
        <C>                        <C>
         November 11, 2002          "ITEM 2.  ACQUISITION  OR  DISPOSITION  OF  ASSETS"  filed by Exelon and
                                    Generation  regarding  the  acquisition  of Sithe New England,  "ITEM 5.
                                    OTHER EVENTS" filed by Exelon and Generation  regarding the Sithe Boston
                                    credit  facility and "ITEM 7. FINANCIAL  STATEMENTS AND EXHIBITS"  filed
                                    by Exelon  and  Generation  for the  financial  statements  of Sithe New
                                    England.


                                                      7
<PAGE>



         January 15, 2003           "ITEM 9.  REGULATION FD  DISCLOSURE"  filed by Exelon,  ComEd,  PECO and
                                    Generation  regarding the confirmation of earnings guidance for 2002 and
                                    2003.

         January 22, 2003           "ITEM 5. OTHER  EVENTS"  filed by ComEd  regarding  the issuance of $700
                                    million in First Mortgage Bonds.

         January 29, 2003           "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding the fourth quarter 2002 earnings release and items
                                    discussed during the Earnings Conference Call.

         February 11, 2003          "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding a presentation by John Rowe,  Chairman and CEO and
                                    Bob Shapard,  Executive Vice President and CFO at the Exelon Corporation
                                    Investor   Update   conference  held  in  New  York  City.  The  exhibit
                                    includes the slides used during the presentation.

         February 21, 2003          "ITEM 5. OTHER  EVENTS"  filed for Exelon  regarding  certain  financial
                                    information  of  Exelon  Corporation  and  Subsidiary   Companies.   The
                                    exhibits  under "ITEM 7.  FINANCIAL  STATEMENT AND  EXHIBITS"  filed for
                                    Exelon  include  the  Consent  of the  Independent  Public  Accountants,
                                    Selected  Financial  Data,  Market for  Registrant's  Common  Equity and
                                    Related  Stockholder  Matters,  Management's  Discussion and Analysis of
                                    Financial Condition and Results of Operations,  and Financial Statements
                                    and Supplementary Data.

         February 26, 2003          "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding a  presentation  by Bob  Shapard,  Executive  Vice
                                    President and CFO and Linda Byus, Vice President  Investor  Relations to
                                    investors  and  information  regarding  the small  and large  commercial
                                    market share threshold  auction in  Pennsylvania.  The exhibits  include
                                    the slides used during the  presentation and materials made available to
                                    investors attending the conference.

         March 3, 2003              "ITEM 5. OTHER  EVENTS"  filed for Exelon,  ComEd,  PECO and  Generation
                                    regarding the reaffirmation of operating  earnings guidance for 2003 and
                                    the discussion of ComEd's agreement regarding rate matters.





                                                      8
<PAGE>


         March 7, 2003              "ITEM 5. OTHER EVENTS" filed for Exelon and Generation regarding the
                                    announcement of the decision not to sell its interest in AmerGen.

         March 13, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding a presentation  by John Rowe,  Chairman and CEO at
                                    the Morgan Stanley Global  Electricity & Energy  Conference  held in New
                                    York  City.   The   exhibit   includes   the  slides   used  during  the
                                    presentation.

         March 14, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding  comments  and  questions  at the  Morgan  Stanley
                                    Global Electricity & Energy Conference.

         March 14, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  to amend the Current  Report filed  earlier in the same day,
                                    in order to clarify  remarks made  regarding  British Energy and AmerGen
                                    at the Morgan Stanley Global Electricity & Energy Conference.

         March 17, 2003             "ITEM  5.  OTHER  EVENTS"  filed  by  ComEd  regarding  the sale of $200
                                    million in Trust Preferred Securities.

         March 26, 2003             "ITEM 9.  REGULATION FD DISCLOSURE"  filed for Exelon,  ComEd,  PECO and
                                    Generation  regarding a presentation by J. Barry  Mitchell,  Senior Vice
                                    President  and  Treasurer at the Banc One Capital  Markets  Fixed Income
                                    Utilities  Conference held in Chicago.  The exhibit  includes the slides
                                    used during the presentation.

         March 28, 2003             "ITEM 5. OTHER EVENTS" filed by Exelon and ComEd  regarding the issuance
                                    of orders by the Illinois  Commerce  Commission  resolving pending cases
                                    and  addressing  key  issues  in  Illinois'  continued  transition  to a
                                    competitive electricity marketplace.
------------------------------------------------------------------------------------------------------------
</TABLE>





                                        9
<PAGE>

                                   SIGNATURES
--------------------------------------------------------------------------------

              Pursuant to 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.

                               EXELON CORPORATION

<TABLE>
<CAPTION>
<C>                                                                   <C>
     /s/ John W. Rowe                                                  /s/ Robert S. Shapard
     ----------------------------------------                          --------------------------------------
     JOHN W. ROWE                                                      ROBERT S. SHAPARD
     Chairman and                                                      Executive Vice President and Chief
     Chief Executive Officer                                           Financial Officer
     (Principal Executive Officer)                                     (Principal Financial Officer)

     /s/ Matthew F. Hilzinger
     ----------------------------------------
     MATTHEW F. HILZINGER
     Vice President and Corporate Controller
     (Principal Accounting Officer)


     December 15, 2003

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

              Pursuant to 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.

                           COMMONWEALTH EDISON COMPANY

     /s/ Michael B. Bemis                                              /s/ J. Barry Mitchell
     ----------------------------------------                          ----------------------------------------
     MICHAEL B. BEMIS                                                  J. BARRY MITCHELL
     President, Exelon Energy Delivery                                 Chief Financial Officer
     (Principal Executive Officer)                                     (Principal Financial Officer)


     /s/ Duane M. DesParte                                             /s/ Frank M. Clark
     ----------------------------------------                          ----------------------------------------
     DUANE M. DESPARTE                                                 FRANK M. CLARK
     Vice President and Controller,                                    President, ComEd
     Exelon Energy Delivery
     (Principal Accounting Officer)

      December 15, 2003



                                       10
<PAGE>

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

              Pursuant to 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.

                                   PECO ENERGY COMPANY

     /s/ Michael B. Bemis                                              /s/ J. Barry Mitchell
     ----------------------------------------                          -------------------------------
     MICHAEL B. BEMIS                                                  J. BARRY MITCHELL
     President, Exelon Energy Delivery                                 Chief Financial Officer
     (Principal Executive Officer)                                     (Principal Financial Officer)


     /s/ Duane M. DesParte                                             /s/ Denis P. O'Brien
     ----------------------------------------                          --------------------------------------
     DUANE M. DESPARTE                                                 DENIS P. O'BRIEN
     Vice President and Controller,                                    President, PECO
     Exelon Energy Delivery
     (Principal Accounting Officer)

      December 15, 2003

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

              Pursuant to 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.

                         EXELON GENERATION COMPANY, LLC

     /s/ Oliver D. Kingsley Jr.                                        /s/ J. Barry Mitchell
     ----------------------------------------                          -------------------------------
     OLIVER D. KINGSLEY JR.                                            J. BARRY MITCHELL
     Chief Executive Officer and                                       Chief Financial Officer
     President                                                         (Principal Financial Officer)
     (Principal Executive Officer)


     /s/ Matthew F. Hilzinger
     ----------------------------------------
     MATTHEW F. HILZINGER
     Vice President and Corporate Controller, Exelon
     (Principal Accounting Officer)

</TABLE>

      December 15, 2003




                                       11
<PAGE>