EXHIBIT A

                                     Allonge


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                     ALLONGE TO REPLACEMENT PROMISSORY NOTE

         This Allonge made this 11th day of January,  1999,  to the  Replacement
Promissory Note dated December 20, 1996 made by The Bank of New York, not in its
individual or corporate  capacity,  but solely in its capacity as Trustee of the
Mid Atlantic Medical Services,  Inc. Stock  Compensation  Trust  ("Borrower") in
favor of Mid Atlantic Medical Services, Inc. ("Lender").

         WHEREAS,  Borrower  executed  and  delivered  to  Lender a  Replacement
Promissory  Note dated  December  20, 1996 in the original  principal  amount of
$129,902,500 (the "Original Note").

         WHEREAS,  $100,091,287.20  of the principal amount of the Original Note
remains unpaid as of the date hereof.

         WHEREAS,  in order to finance  the  Borrower's  purchase  of  1,500,000
shares of the  Lender's  common  stock  pursuant  to the  terms of Common  Stock
Purchase  Agreement  of even date  herewith  between  the  Borrower  and Lender,
Borrower and Lender wish to increase the  principal  amount of the Original Note
due and owing from  $100,091,287.20 to  $118,076,287.20  while leaving all other
terms of the Original Note unamended.

         NOW, THEREFORE, for good and valuable consideration and intending to be
legally bound hereby, the parties hereto agree as follows:

                  (1) The  Original  Note is  hereby  amended  by  deleting  all
         references  to   "$129,902,500"   and  by  inserting  in  lieu  thereof
         "$118,076,287.20."

                  (2) The last sentence of the second  paragraph of the Original
         Note is hereby  amended by deleting the date "December 20, 1996" and by
         inserting in lieu thereof January 11, 1999."

                  (3) Schedule A attached to the Original Note is hereby amended
         and restated in its entirety in the form attached hereto as Exhibit 1.

                  (4) Schedule B attached to the Original Note is hereby amended
         and restated in its entirety in the form attached hereto as Exhibit 2.

                  (5) Except as expressly amended hereby, the Original Note
         shall remain unamended and in full force and effect.

         IN WITNESS  WHEREOF,  this Allonge to  Replacement  Promissory  is made
effective as of the 11th day of January, 1999.


Attest:                     THE BANK OF NEW YORK, not in its individual
                            corporate capacity, but solely in its capacity as
                            Trustee of the Mid Atlantic Medical Services, Inc.
                            Stock Compensation Trust

  /s/ Paulette S. Bazil                       By:  /s/ Richard J. Barry   

                                              Title:  Vice President


Attest:                                      MID ATLANTIC MEDICAL SERVICES, INC.

  /s/ Alisa Chestler                           By:  /s/ Sharon C. Pavlos

                                               Title:  Senior Vice President, 
                                                       General Counsel       
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                               EXHIBIT 1

 Trust Year                      Amount

    1999                      9,000,000.00
    2000                      9,000,000.00
    2001                      9,000,000.00
    2002                      9,000,000.00
    2003                      9,000,000.00
    2004                      9,000,000.00
    2005                      9,000,000.00
    2006                      9,000,000.00
    2007                      9,000,000.00
    2008                      9,000,000.00
    2009                      9,000,000.00
    2010                      9,000,000.00
    2011                     10,076,287.20



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                                    Exhibit 2
                              Interest
  Pay Date       Year          Amount
     1/5      1999               2,017,812
    4/15                         2,361,526
    7/15                         2,317,526
    10/15                        2,271,526
     1/5      2000               2,227,526
    4/15                         2,181,526
    7/15                         2,137,526
    10/15                        2,091,526
     1/5      2001               2,047,526
    4/15                         2,001,526
    7/15                         1,957,526
    10/15                        1,911,526
     1/5      2002               1,867,526
    4/15                         1,821,526
    7/15                         1,777,526
    10/15                        1,731,526
     1/5      2003               1,687,526
    4/15                         1,641,526
    7/15                         1,597,526
    10/15                        1,551,526
     1/5      2004               1,507,526
    4/15                         1,461,526
    7/15                         1,417,526
    10/15                        1,371,526
     1/5      2005               1,327,526
    4/15                         1,281,526
    7/15                         1,237,526
    10/15                        1,191,526
     1/5      2006               1,147,526
    4/15                         1,101,526
    7/15                         1,057,526
    10/15                        1,011,526
     1/5      2007                 967,526
    4/15                           921,526
    7/15                           877,526
    10/15                          831,526
     1/5      2008                 787,526
    4/15                           741,526
    7/15                           697,526
    10/15                          651,526
     1/5      2009                 607,526
    4/15                           561,526
    7/15                           517,526
    10/15                          471,526
     1/5      2010                 427,526
    4/15                           381,526
    7/15                           337,526
    10/15                          291,526
     1/5      2011                 247,526
    4/15                           201,526
    7/15                           152,637
    8/26                            46,251
                                65,035,474