MEDIMMUNE SHAREHOLDERS CLEAR THE WAY FOR
                            THREE-FOR-ONE STOCK SPLIT

Gaithersburg, MD, May 18, 2000 -- MedImmune, Inc. (Nasdaq: MEDI) announced today
that at its Annual  Shareholders'  Meeting,  shareholders  voted to increase the
number of  authorized  shares of MedImmune  common stock from 120 million to 320
million.  This action was a prerequisite for the company's  previously announced
three-for-one stock split to proceed.

MedImmune's  three-for-one stock split will be paid in the form of a 200-percent
stock dividend to all shareholders of record at the close of business on May 18,
2000. This stock dividend provides  shareholders two additional shares for every
share owned.  Distribution of the new shares will occur on or about Friday, June
2, 2000.  Shareholders who hold their stock in a brokerage account, will receive
their  new  shares   through  their  broker  who  will  credit  their   account.
Shareholders who maintain physical  possession of their stock  certificates will
have their  additional  shares mailed to them.  The  company's  stock will begin
trading at the  post-split  price on Monday,  June 5,  2000.  Any shares  traded
between May 18 and June 5 will come with a "due-bill" entitling the buyer to two
additional  shares for each share purchased that will be distributed on or about
June 7.

As of March 31, 1999,  MedImmune had  approximately  70 million shares of common
stock outstanding.  Following the split, the company will have approximately 210
million shares outstanding.

MedImmune,   Inc.  is  a  fully  integrated  biotechnology  company  focused  on
developing  and marketing  products that address  medical needs in areas such as
infectious disease, immune regulation and cancer. Headquartered in Gaithersburg,
Maryland,  MedImmune has  manufacturing  facilities  in Frederick,  Maryland and
Nijmegen,  the  Netherlands,  and an oncology  subsidiary in West  Conshohocken,
Pennsylvania.

This announcement may contain,  in addition to historical  information,  certain
forward-looking statements that involve risks and uncertainties. Such statements
reflect management's current views and are based on certain assumptions.  Actual
results could differ materially from those currently  anticipated as a result of
a  number  of  factors,  including  risks  and  uncertainties  discussed  in the
company's filings with the U.S.  Securities and Exchange  Commission.  MedImmune
cautions that RSV disease occurs primarily during the winter months; the company
believes its operating results will reflect that seasonality for the foreseeable
future.  The company is also developing  several  products for potential  future
marketing. There can be no assurance that such development efforts will succeed,
that such products will receive required  regulatory  clearance or that, even if
such regulatory clearance were received,  such products would ultimately achieve
commercial success.

                                   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 hereonto duly authorized.

                                MEDIMMUNE, INC.
                               ----------------
                                  (Registrant)

June 2, 2000 By:

                               -----------------
                          David M. Mott, Vice Chairman
                           and Chief Financial Officer
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MEDIMMUNE SHAREHOLDERS CLEAR THE WAY FOR
                            THREE-FOR-ONE STOCK SPLIT

Gaithersburg, MD, May 18, 2000 -- MedImmune, Inc. (Nasdaq: MEDI) announced today
that at its Annual  Shareholders'  Meeting,  shareholders  voted to increase the
number of  authorized  shares of MedImmune  common stock from 120 million to 320
million.  This action was a prerequisite for the company's  previously announced
three-for-one stock split to proceed.

MedImmune's  three-for-one stock split will be paid in the form of a 200-percent
stock dividend to all shareholders of record at the close of business on May 18,
2000. This stock dividend provides  shareholders two additional shares for every
share owned.  Distribution of the new shares will occur on or about Friday, June
2, 2000.  Shareholders who hold their stock in a brokerage account, will receive
their  new  shares   through  their  broker  who  will  credit  their   account.
Shareholders who maintain physical  possession of their stock  certificates will
have their  additional  shares mailed to them.  The  company's  stock will begin
trading at the  post-split  price on Monday,  June 5,  2000.  Any shares  traded
between May 18 and June 5 will come with a "due-bill" entitling the buyer to two
additional  shares for each share purchased that will be distributed on or about
June 7.

As of March 31, 1999,  MedImmune had  approximately  70 million shares of common
stock outstanding.  Following the split, the company will have approximately 210
million shares outstanding.

MedImmune,   Inc.  is  a  fully  integrated  biotechnology  company  focused  on
developing  and marketing  products that address  medical needs in areas such as
infectious disease, immune regulation and cancer. Headquartered in Gaithersburg,
Maryland,  MedImmune has  manufacturing  facilities  in Frederick,  Maryland and
Nijmegen,  the  Netherlands,  and an oncology  subsidiary in West  Conshohocken,
Pennsylvania.

This announcement may contain,  in addition to historical  information,  certain
forward-looking statements that involve risks and uncertainties. Such statements
reflect management's current views and are based on certain assumptions.  Actual
results could differ materially from those currently  anticipated as a result of
a  number  of  factors,  including  risks  and  uncertainties  discussed  in the
company's filings with the U.S.  Securities and Exchange  Commission.  MedImmune
cautions that RSV disease occurs primarily during the winter months; the company
believes its operating results will reflect that seasonality for the foreseeable
future.  The company is also developing  several  products for potential  future
marketing. There can be no assurance that such development efforts will succeed,
that such products will receive required  regulatory  clearance or that, even if
such regulatory clearance were received,  such products would ultimately achieve
commercial success.

                                   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 hereonto duly authorized.

                                MEDIMMUNE, INC.
                               ----------------
                                  (Registrant)

June 2, 2000 By:

                               -----------------
                          David M. Mott, Vice Chairman
                           and Chief Financial Officer