SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 8-K


                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                       Date of Report: September 22, 1999



                                 MEDIMMUNE, INC.
             (Exact name of registrant as specified in its charter)



                         Commission File Number: 0-19131




                       Delaware                   52-1555759
              (State of Incorporation)         (I.R.S. Employer
                                              Identification No.)



                35 West Watkins Mill Road, Gaithersburg, MD 20878
                (Address of principal executive office (Zip Code)


Registrant's telephone number, including area code (301) 417-0770


No Exhibits are being filed with this report


CytoGam and RespiGam are  registered  trademarks of the Company and Synagis is a
trademark.

<PAGE>

MEDIMMUNE, INC.
Current Report on Form 8-K


ITEM 5.  OTHER EVENTS

MedImmune,  Inc.  reported  the  information  contained in the  following  press
release dated September 22, 1999:



                MEDIMMUNE, Inc. to Acquire U.S. Bioscience, Inc.
    -Acquisition Provides Immediate Products and Infrastructure in Oncology-

Gaithersburg,  MD and West  Conshohocken,  PA, Sept. 22, 1999 - MedImmune,  Inc.
(Nasdaq:  MEDI) and U.S. Bioscience,  Inc. (Amex: UBS) announced today that they
have  entered  into  a  definitive  agreement  for  MedImmune  to  acquire  U.S.
Bioscience,  a  specialty  pharmaceutical  company  that  develops  and  markets
products for patients with cancer and AIDS. MedImmune expects the transaction to
be neutral to earnings in year 2000 and accretive thereafter.

Under  the  terms  of  the  agreement,   MedImmune  will  acquire  all  of  U.S.
Bioscience's  outstanding shares in a tax-free,  stock-for-stock  merger that is
intended to be accounted for under  pooling-of-interests  treatment.  The equity
value is $492 million or a transaction value of approximately  $440 million (net
of cash)  based on an average  MedImmune  stock price of $110 per share and 29.8
million fully diluted U.S.  Bioscience  shares.  The exchange ratio will be 0.15
MedImmune shares per U.S. Bioscience share,  subject to adjustment  depending on
the average  closing price of MedImmune  over the 20-day  trading  period ending
three days prior to the U.S.  Bioscience  shareholder  meeting to  consider  the
merger.

If  MedImmune's  average  share  price is greater  than $140  during this 20-day
period,  the exchange  ratio shall be $19.10 divided by the average share price.
If MedImmune's  average share price is greater than $132, but less than or equal
to $140 the exchange ratio shall be 0.1364.  If MedImmune's  average share price
is $132 or lower,  but more than $120, the exchange ratio will be $18 divided by
MedImmune's  average share price.  If MedImmune's  share price is $100 or lower,
but more than $88,  the  exchange  ratio  shall be $15  divided  by  MedImmune's
average share price,  and if the average share price is lower than $88, but more
than $80 the exchange ratio shall be 0.1705. If MedImmune's  average share price
is less than $80, U.S.  Bioscience  may terminate  the merger  agreement  unless
MedImmune  delivers  a notice to the effect  that the  exchange  ratio  shall be
$13.64 divided by the average share price.

The Boards of  Directors  of both  MedImmune  and U.S.  Bioscience  approved the
proposed  merger,  which is  subject to  customary  conditions,  including  U.S.
Bioscience  stockholder approval and antitrust  clearance.  The merger agreement
provides that U.S. Bioscience pay MedImmune a $15 million termination fee and up
to $2 million in  expenses,  under  certain  circumstances.  In  addition,  as a
condition to entering into the transaction,  MedImmune required U.S.  Bioscience
to grant it an option to purchase up to 19.9% of U.S.  Bioscience's  outstanding
shares.  The companies  anticipate that the transaction will close in the fourth
quarter of 1999 or the first quarter of 2000.
<PAGE>

"We  are  delighted  with  this  transaction,"  said  Dr.  Wayne  T.  Hockmeyer,
MedImmune's  chairman and chief executive  officer.  "This  acquisition  further
solidifies  MedImmune's  commitment to the field of oncology. It will provide us
with three marketed  products in the fields of oncology and infectious  disease,
as  well  as  development  capabilities  and an  oncology  sales  and  marketing
infrastructure.  Earlier  this year we expanded our  strategic  focus to include
oncology  products  with the  acquisition  of  Vitaxin(Trademark),  a  humanized
anti-angiogenesis monoclonal antibody now in Phase 2 clinical trials."

U.S.  Bioscience's product portfolio includes  Ethyol(Registered)  (amifostine),
which is approved for the reduction of  cumulative  kidney  toxicity  associated
with repeated  administration  of cisplatin in patients  with  advanced  ovarian
cancer and non-small cell lung cancer.  Additionally,  in June 1999 the drug was
approved by the FDA for use in the  reduction of  moderate-to-severe  xerostomia
(chronic dry mouth) in patients  undergoing  post-operative  radiation treatment
for  head  and  neck  cancer.   Other  products  include   NeuTrexin(Registered)
(trimetrexate   glucuronate   for   injection),   which   is   used   to   treat
moderate-to-severe  Pneumocystis  carinii pneumonia in patients with compromised
immune systems and is in clinical development for metastatic  colorectal cancer,
and  Hexalen(Registered)(altretamine),  a second-line chemotherapy used to treat
patients with persistent or recurrent ovarian cancer.  Lodenosine,  a nucleoside
reverse transcriptase inhibitor is in Phase 2 clinical trials with the potential
to treat HIV infection.

C. Boyd Clarke, president and chief executive officer of U.S. Bioscience,  said,
"We're  extremely  pleased to join forces with MedImmune and proud to strengthen
the  foundation  and growth  prospects of  MedImmune's  oncology  franchise.  We
anticipate that  Ethyol(Registered)(amifostine) will be a meaningful product for
MedImmune  following  our  merger.  We are  eager to use our  people,  pipeline,
clinical  expertise  and  manufacturing  capacity  to  continue  to add value to
MedImmune."

U.S.  Bioscience,  Inc.,  based  in  West  Conshohocken,   Pennsylvania,   is  a
pharmaceutical  company specializing in the development and commercialization of
products for patients  with cancer and AIDS.  The company has three  products on
the market. In addition to its headquarters, U.S. Bioscience has a manufacturing
facility  located in Nijmegen,  The  Netherlands,  an  analytical  laboratory in
Exton,  PA.,  and a  subsidiary  near London to  coordinate  clinical  trials in
Europe.

MedImmune,  Inc. located in Gaithersburg,  Maryland,  is a biotechnology company
focused on developing and marketing products that address medical needs in areas
such as infectious disease,  transplantation medicine,  autoimmune disorders and
cancer.  MedImmune markets three products through its hospital-based sales force
and has five new product candidates in clinical trials.

Statements about the proposed merger are forward-looking statements that involve
risks and  uncertainties.  Among the factors that could cause actual  results of
MedImmune,  U.S.  Bioscience or the combined  company to differ  materially from
those in the forward  looking  statements  are:  the failure of the merger to be
consummated, the ability of the companies to successfully integrate,  challenges
inherent  in new  product  development  and  marketing,  governmental  laws  and
regulations, including possible healthcare reform, the availability of favorable
tax and accounting  treatment for the merger and those factors in the companies'
reports  and filings  with the U.S.  Securities  and  Exchange  Commission.  The
companies  disclaim  any  intention  or  obligation  to  update  or  revise  any
forward-looking statements.
<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 hereunto duly authorized.


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



 September 22, 1999        /s/David M. Mott
                           David M. Mott, Vice Chairman and
                           Chief Financial Officer
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SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
                       Date of Report: September 22, 1999

                                 MEDIMMUNE, INC.
             (Exact name of registrant as specified in its charter)

                         Commission File Number: 0-19131

                       Delaware                   52-1555759
              (State of Incorporation)         (I.R.S. Employer
                                              Identification No.)

                35 West Watkins Mill Road, Gaithersburg, MD 20878
                (Address of principal executive office (Zip Code)

Registrant's telephone number, including area code (301) 417-0770

No Exhibits are being filed with this report

CytoGam and RespiGam are  registered  trademarks of the Company and Synagis is a
trademark.
MEDIMMUNE, INC.
Current Report on Form 8-K

ITEM 5.  OTHER EVENTS

MedImmune,  Inc.  reported  the  information  contained in the  following  press
release dated September 22, 1999:

                MEDIMMUNE, Inc. to Acquire U.S. Bioscience, Inc.
    -Acquisition Provides Immediate Products and Infrastructure in Oncology-

Gaithersburg,  MD and West  Conshohocken,  PA, Sept. 22, 1999 - MedImmune,  Inc.
(Nasdaq:  MEDI) and U.S. Bioscience,  Inc. (Amex: UBS) announced today that they
have  entered  into  a  definitive  agreement  for  MedImmune  to  acquire  U.S.
Bioscience,  a  specialty  pharmaceutical  company  that  develops  and  markets
products for patients with cancer and AIDS. MedImmune expects the transaction to
be neutral to earnings in year 2000 and accretive thereafter.

Under  the  terms  of  the  agreement,   MedImmune  will  acquire  all  of  U.S.
Bioscience's  outstanding shares in a tax-free,  stock-for-stock  merger that is
intended to be accounted for under  pooling-of-interests  treatment.  The equity
value is $492 million or a transaction value of approximately  $440 million (net
of cash)  based on an average  MedImmune  stock price of $110 per share and 29.8
million fully diluted U.S.  Bioscience  shares.  The exchange ratio will be 0.15
MedImmune shares per U.S. Bioscience share,  subject to adjustment  depending on
the average  closing price of MedImmune  over the 20-day  trading  period ending
three days prior to the U.S.  Bioscience  shareholder  meeting to  consider  the
merger.

If  MedImmune's  average  share  price is greater  than $140  during this 20-day
period,  the exchange  ratio shall be $19.10 divided by the average share price.
If MedImmune's  average share price is greater than $132, but less than or equal
to $140 the exchange ratio shall be 0.1364.  If MedImmune's  average share price
is $132 or lower,  but more than $120, the exchange ratio will be $18 divided by
MedImmune's  average share price.  If MedImmune's  share price is $100 or lower,
but more than $88,  the  exchange  ratio  shall be $15  divided  by  MedImmune's
average share price,  and if the average share price is lower than $88, but more
than $80 the exchange ratio shall be 0.1705. If MedImmune's  average share price
is less than $80, U.S.  Bioscience  may terminate  the merger  agreement  unless
MedImmune  delivers  a notice to the effect  that the  exchange  ratio  shall be
$13.64 divided by the average share price.

The Boards of  Directors  of both  MedImmune  and U.S.  Bioscience  approved the
proposed  merger,  which is  subject to  customary  conditions,  including  U.S.
Bioscience  stockholder approval and antitrust  clearance.  The merger agreement
provides that U.S. Bioscience pay MedImmune a $15 million termination fee and up
to $2 million in  expenses,  under  certain  circumstances.  In  addition,  as a
condition to entering into the transaction,  MedImmune required U.S.  Bioscience
to grant it an option to purchase up to 19.9% of U.S.  Bioscience's  outstanding
shares.  The companies  anticipate that the transaction will close in the fourth
quarter of 1999 or the first quarter of 2000.
"We  are  delighted  with  this  transaction,"  said  Dr.  Wayne  T.  Hockmeyer,
MedImmune's  chairman and chief executive  officer.  "This  acquisition  further
solidifies  MedImmune's  commitment to the field of oncology. It will provide us
with three marketed  products in the fields of oncology and infectious  disease,
as  well  as  development  capabilities  and an  oncology  sales  and  marketing
infrastructure.  Earlier  this year we expanded our  strategic  focus to include
oncology  products  with the  acquisition  of  Vitaxin(Trademark),  a  humanized
anti-angiogenesis monoclonal antibody now in Phase 2 clinical trials."

U.S.  Bioscience's product portfolio includes  Ethyol(Registered)  (amifostine),
which is approved for the reduction of  cumulative  kidney  toxicity  associated
with repeated  administration  of cisplatin in patients  with  advanced  ovarian
cancer and non-small cell lung cancer.  Additionally,  in June 1999 the drug was
approved by the FDA for use in the  reduction of  moderate-to-severe  xerostomia
(chronic dry mouth) in patients  undergoing  post-operative  radiation treatment
for  head  and  neck  cancer.   Other  products  include   NeuTrexin(Registered)
(trimetrexate   glucuronate   for   injection),   which   is   used   to   treat
moderate-to-severe  Pneumocystis  carinii pneumonia in patients with compromised
immune systems and is in clinical development for metastatic  colorectal cancer,
and  Hexalen(Registered)(altretamine),  a second-line chemotherapy used to treat
patients with persistent or recurrent ovarian cancer.  Lodenosine,  a nucleoside
reverse transcriptase inhibitor is in Phase 2 clinical trials with the potential
to treat HIV infection.

C. Boyd Clarke, president and chief executive officer of U.S. Bioscience,  said,
"We're  extremely  pleased to join forces with MedImmune and proud to strengthen
the  foundation  and growth  prospects of  MedImmune's  oncology  franchise.  We
anticipate that  Ethyol(Registered)(amifostine) will be a meaningful product for
MedImmune  following  our  merger.  We are  eager to use our  people,  pipeline,
clinical  expertise  and  manufacturing  capacity  to  continue  to add value to
MedImmune."

U.S.  Bioscience,  Inc.,  based  in  West  Conshohocken,   Pennsylvania,   is  a
pharmaceutical  company specializing in the development and commercialization of
products for patients  with cancer and AIDS.  The company has three  products on
the market. In addition to its headquarters, U.S. Bioscience has a manufacturing
facility  located in Nijmegen,  The  Netherlands,  an  analytical  laboratory in
Exton,  PA.,  and a  subsidiary  near London to  coordinate  clinical  trials in
Europe.

MedImmune,  Inc. located in Gaithersburg,  Maryland,  is a biotechnology company
focused on developing and marketing products that address medical needs in areas
such as infectious disease,  transplantation medicine,  autoimmune disorders and
cancer.  MedImmune markets three products through its hospital-based sales force
and has five new product candidates in clinical trials.

Statements about the proposed merger are forward-looking statements that involve
risks and  uncertainties.  Among the factors that could cause actual  results of
MedImmune,  U.S.  Bioscience or the combined  company to differ  materially from
those in the forward  looking  statements  are:  the failure of the merger to be
consummated, the ability of the companies to successfully integrate,  challenges
inherent  in new  product  development  and  marketing,  governmental  laws  and
regulations, including possible healthcare reform, the availability of favorable
tax and accounting  treatment for the merger and those factors in the companies'
reports  and filings  with the U.S.  Securities  and  Exchange  Commission.  The
companies  disclaim  any  intention  or  obligation  to  update  or  revise  any
forward-looking statements.
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 hereunto duly authorized.

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

 September 22, 1999        /s/David M. Mott
                           David M. Mott, Vice Chairman and
                           Chief Financial Officer