FILED BY:  MID ATLANTIC MEDICAL SERVICES, INC.
                           PURSUANT TO RULE 425 UNDER THE SECURITIES ACT OF 1933
 AND DEEMED FILED PURSUANT TO RULE 14a-12 OF THE SECURITIES EXCHANGE ACT OF 1934

                           SUBJECT COMPANY:  MID ATLANTIC MEDICAL SERVICES, INC.
                                                     COMMISSION FILE NO. 1-13340


                          IMPORTANT MERGER INFORMATION
                          ----------------------------

      In connection with the proposed transaction, UnitedHealth Group
Incorporated ("UnitedHealth Group") and Mid Atlantic Medical Services, Inc.
("MAMSI") have filed relevant materials with the Securities and Exchange
Commission ("SEC"), including a registration statement that contains a
definitive proxy statement/prospectus, which was filed on January 20, 2004. The
definitive proxy statement/prospectus has been sent to holders of MAMSI common
stock. Holders of MAMSI common stock are urged to read the definitive proxy
statement/prospectus and any other relevant materials filed by UnitedHealth
Group or MAMSI with the SEC because they contain, or will contain, important
information about UnitedHealth Group, MAMSI and the transaction. The definitive
proxy statement/prospectus is available for free (along with any other documents
and reports filed by UnitedHealth Group and MAMSI with the SEC) at the SEC's
website, www.sec.gov. In addition, you may obtain documents filed with the SEC
by MAMSI free of charge by requesting them in writing from Mid Atlantic Medical
Services, Inc., 4 Taft Court, Rockville, Maryland, 20850, Attention: Corporate
Secretary, or by telephone at (301) 762-8205. You may obtain documents filed
with the SEC by UnitedHealth Group free of charge by requesting them in writing
from UnitedHealth Group Incorporated, UnitedHealth Group Center, 9900 Bren Road
East, Minnetonka, Minnesota 55343, Attention: Corporate Secretary, or by
telephone at (952) 936-1300.

      MAMSI and its directors and executive officers may be deemed to be
participants in the solicitation of proxies from the holders of MAMSI common
stock in connection with the proposed transaction. Information about the
ownership of MAMSI common stock by directors and executive officers of MAMSI, as
well as additional information regarding the interests of such participants, is
set forth in the definitive proxy statement/prospectus.

      UnitedHealth Group and its directors and executive officers may be deemed
to be participants in the solicitation of proxies from the holders of MAMSI
common stock in connection with the proposed transaction. Information about the
directors and executive officers of UnitedHealth Group, as well as additional
information regarding the interests of such participants, is set forth in the
definitive proxy statement/prospectus.

      This communication shall not constitute an offer to sell or the
solicitation of an offer to buy any securities, nor shall there be any sale of
securities in any jurisdiction in which such offer, solicitation or sale would
be unlawful prior to registration or qualification under the securities laws of
any such jurisdiction. No offering of securities shall be made except by means
of a prospectus meeting the requirements of Section 10 of the Securities Act of
1933, as amended.



                           FORWARD-LOOKING STATEMENTS
                           --------------------------

      This document may contain statements, estimates or projections that
constitute "forward-looking" statements as defined under U.S. federal securities
laws. Generally the words "believe," "expect," "intend," "estimate,"
"anticipate," "project," "will" and similar expressions identify forward-looking
statements, which generally are not historical in nature. By their nature,
forward-looking statements are subject to risks and uncertainties that could
cause actual results to differ materially from our historical experience and our
present expectations or projections. A list and description of some of the risks
and uncertainties can be found in our reports filed with the SEC from time to
time, including our annual reports on Form 10-K, quarterly reports on Form 10-Q
and current reports on Form 8-K. You should not place undue reliance on
forward-looking statements, which speak only as of the date they are made.
Except to the extent otherwise required by federal securities laws, we do not
undertake to publicly update or revise any forward-looking statements.


                       Supplemental Memorandum Concerning
                       ----------------------------------
                            Exercise of Stock Options
                            -------------------------


TO:            All MAMSI Option Holders

DATE:          February 6, 2004

RE:            Exercise of Stock Options

================================================================================

      THIS DOCUMENT CONSTITUTES PART OF A PROSPECTUS COVERING SECURITIES THAT
      HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933.

      On January 14, 2004, you received a Memorandum describing the various
methods available to option holders who exercise their MAMSI stock options in
relation to the proposed merger ("Merger") of MAMSI with a subsidiary of United
Health Group Incorporated ("UHG"). An additional feature described in the
Memorandum is the "special cash election", in which an option holder can elect
to have the portion of the the Merger consideration consisting of UHG shares
sold for cash. For option holders that selected the "special cash election"
method, this Supplemental Memorandum clarifies the manner in which the option
holders' shares of UHG stock will be sold.



      On the first trading day on the New York Stock Exchange ("NYSE") on which
your UHG shares received may be sold, MAMSI will instruct Smith Barney to sell
your shares through a conventional market order at the then current market price
on the NYSE. However, if many option holders select the special cash election
feature and a large number of UHG shares are therefore to be sold, MAMSI may
determine (after consultation with Smith Barney) that the sale of a large amount
of UHG stock through a conventional market order could potentially have an
adverse effect on the price at which the UHG shares may be sold. In order to
seek to minimize any adverse market impact of such a sale, MAMSI may instruct
Smith Barney to sell the UHG shares in one of the following ways, each of which
is a well-recognized and widely-accepted selling method. MAMSI has determined
that either trading method, if selected, may be appropriate, depending upon
market conditions prevailing at the time of sale.

      1.) AVERAGE PRICE TRADE: All orders to sell the UHG stock will be
      aggregated. Rather than selling the entire amount of UHG stock at the same
      time, MAMSI may instruct Smith Barney to sell the stock on an agency basis
      in various lots over time. This method gives Smith Barney as the selling
      broker the flexibility to react to changing market conditions in a manner
      that is least disruptive to the stock's trading environment. Although the
      stock will be sold in multiple executions, you will receive one average
      price rather than the actual market prices at which the executions took
      place. Some of the actual sale prices will be higher than the average
      price and some will be lower. In the event Smith Barney is unable to sell
      in multiple trades on the same trading day the total number of UHG shares
      to be sold pursuant to MAMSI's instructions, Smith Barney will sell the
      remaining shares in one or more trades on the immediately succeeding
      trading day or days on the NYSE.

      2.) BLOCK TRADE: In a block trade, Smith Barney will buy all the UHG
      shares for its own account in one large block. Since Smith Barney will
      then own all the shares, the risk of price fluctuation in the UHG stock is
      transferred from you to Smith Barney. To compensate Smith Barney for
      taking this risk, Smith Barney will purchase the block at a discount to
      the market price of the UHG stock at the time of purchase. The amount of
      the discount will depend on market conditions at the time of the sale.
      Each option holder will receive the same single price (i.e., the then
      current market price minus the discount) for the UHG shares sold.



      Option holders whose sales must be effected pursuant to Rule 145 under the
Securities Act of 1933 as a result of the Merger may sell their UHG shares
pursuant to an average price or block trade. In order to comply with Rule 145,
however, such trades on behalf of optionholders covered by this Rule will be
conducted separately from any average price or block trade conducted on behalf
of optionholders whose sales of UHG stock are not covered by the Rule. Such
persons will be contacted separately.

      The foregoing is intended to give you additional information regarding the
implementation of your election to receive all cash rather than UHG shares and
cash in connection with the Merger, and is not otherwise intended to change the
way in which your options may be exercised as explained in prior communications
to you. Nevertheless, if you wish to change your choice of the "special cash
election" based upon the foregoing disclosure, you may do so by sending a new
Stock Option Election Form to Ellen Hurtt no later than 5:00 pm Eastern Standard
Time on February 9, 2004. A copy of this Form is available from Ellen Hurtt. If
you do not send a new Stock Option Election Form by this deadline, your choice
of the "special cash election" will remain in effect. Any questions concerning
this Supplemental Memorandum should be directed to Ellen Hurtt at (301)
294-5077.