EXHIBIT 10.62
                                
                    FOURTH AMENDMENT OF LEASE

          THIS FOURTH AMENDMENT OF LEASE (this "Amendment") is
made this 3rd day of October, 1996 (the "Effective Date") by and
between CLOPPER ROAD ASSOCIATES, a Maryland joint venture
("Landlord"), and MEDIMMUNE, INC., a Delaware corporation
("Tenant").

                      EXPLANATORY STATEMENT

     A.   Landlord and Tenant entered into a Lease Agreement
dated February 14, 1991 (the "Original Lease"), whereby Tenant
agreed to lease from Landlord Forty Thousand Eight Hundred Forty-
Three (40,843) square feet (the "Original Leased Premises") in
the building (the "Building") known as Building D, located at
35 West Watkins Mill Road, in the Bennington Corporate Center in
Gaithersburg, Maryland.

     B.   Landlord and Tenant entered into a First Amendment of
Lease dated June 8, 1993 (the "First Amendment"), pursuant to
which Building D was expanded and the square footage of the
Original Leased Premises was increased by the amount of such
expansion (the "Expansion Space") (collectively, the Original
Leased Premises and the Expansion Space shall be hereinafter
referred to as the "Expanded Leased Premises"). Certain other
changes were also made to the Original Lease as a result of the
First Amendment.

     C.   Landlord and Tenant entered into a Second Amendment of
Lease dated June 30, 1993 (the "Second Amendment"), pursuant to
which the square footage of the Expanded Leased Premises was
increased by adding space (the "Second Expansion Space") in
Building B located at 25 West Watkins Mill Road in the Bennington
Corporate Center in Gaithersburg, Maryland (collectively, the
Original Leased Premises, the Expansion Space and the Second
Expansion Space are hereinafter referred to as the "Leased
Premises"); the Rent payable was adjusted, and certain other
changes were made to the Original Lease.

     D.   Landlord and Tenant entered into a Third Amendment of
Lease dated April 15, 1996, but effective as of January 1, 1995
(the "Third Amendment") to adjust square footages, percentages
and addresses set forth in the Original Lease as amended.

     E.   The Original Lease and the First, Second and Third
Amendments are herein collectively referred to as the "Lease."

     F.   As a result of the termination of a lease for space
adjoining the portion of the Leased Premises in Building B,
Landlord and Tenant desire to expand the Leased Premises in
Building B, adjust the square footages and percentages in the
Lease, and modify certain other provisions of the Lease, as more
specifically set forth below.

     NOW, THEREFORE, in consideration of the Explanatory
Statement, which is deemed a substantive part of this Fourth
Amendment, the covenants of the parties herein and in the Lease
and other good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, Landlord and Tenant
hereby agree as follows:

     1.   Effective Date of Fourth Amendment. From and after the
date of this Fourth Amendment, the Lease shall be amended as set
forth below.

     2.   Capitalized Terms. All capitalized terms in this Fourth
Amendment shall have the same meanings as those in the Lease,
unless specifically set forth otherwise herein.

     3.   VAD Space.  Landlord hereby leases to Tenant, and
Tenant hereby leases from Landlord, in addition to the Leased
Premises, approximately Eleven Thousand Four Hundred Fifty-Five
(11,455) rentable square feet in Building B (the "VAD Space").
The VAD Space is shown more particularly on Exhibit A attached
hereto and made a part hereof.

     4.   Condition of VAD Space.  The Tenant hereby accepts the
VAD Space in "AS-IS" condition, subject to the VAD Space
Construction as described below and subject to Landlord's duties
otherwise provided herein.

     5.   VAD Space Construction.

          a. VAD Space Plans. Landlord shall cause the tenant
improvements for the VAD Space as defined below (the "VAD Space
Construction" ) to be constructed. Landlord shall provide all
work, labor and materials in support of the VAD Space
Construction in accordance with the plans and specifications for
the VAD Space (the "VAD Space Plans"), which VAD Space Plans have
been approved and initialed by the parties. The VAD Space Plans
are described more fully on Exhibit B attached hereto and made a
part hereof. Tenant may occupy the VAD Space during the VAD Space
Construction; provided that Tenant shall cooperate with Landlord
and Landlord's employees, contractors and subcontractors to
ensure that Tenant's occupancy shall not interfere with the VAD
Space Construction.

          Landlord shall contribute a maximum of Eighty-Five
Thousand Nine Hundred Twelve Dollars and Fifty Cents ($85,912.50)
("Landlord's Contribution") toward the cost of the VAD Space
Construction. If the cost of such Construction exceeds Landlord's
Contribution, then Tenant shall pay the excess cost to Landlord
within thirty (30) days of receipt of an invoice or invoices
therefor from Landlord.

          b.  Change Orders. Any Tenant-generated change orders
to the VAD Space Plans shall be approved by Landlord, which
approval shall not be unreasonably withheld or delayed. If the
cost of the VAD Space Construction is increased due to any one or
more such change orders, Tenant shall pay Landlord such increased
cost within thirty (30) days of Tenant's receipt of an invoice
therefor from Landlord.

          c. Landlord's VAD Space Warranty. At the termination of
Landlord's VAD Space Warranty Period (as defined below), Landlord
hereby agrees to and will assign to Tenant, to the extent they
are assignable, any and all written warranties and guarantees
from Landlord's contractors, subcontractors and suppliers of any
materials and labor to the VAD Space, for that portion, if any,
of the Lease Term that such warranties and guarantees are in
effect. Landlord hereby warrants ("Landlord's VAD Space
Warranty") to Tenant that Landlord will be responsible for a
period ("Landlord's VAD Space Warranty Period" ) of one (1) year
from the VAD Space Commencement Date (as defined below) to repair
or to have repaired all defects in the VAD Space Construction, to
the extent such defects are not caused by the negligence of
Tenant or any of its agents, servants, employees or contractors
(in which event such defects will be repaired at Tenant's sole
cost). To the extent that Landlord is obligated to make repairs
pursuant to Landlord's VAD Space Warranty, Tenant will be
relieved during Landlord's VAD Space Warranty Period of the
obligations imposed upon it pursuant to this Fourth Amendment to
make or pay for such repairs to the VAD Space. Tenant agrees to
and will give Landlord prompt notice of the need for any such
repairs.

     6.   Construction Provisions of Original Leased Premises Not
Applicable to Expansion Space. Article I.B of the Original Lease,
Paragraphs 4 through 7 of the First Amendment, and Paragraph 5 of
the Second Amendment shall not apply to the VAD Space, except as
specifically set forth in this Fourth Amendment.

     7.   Term of VAD Space Lease.  The VAD Space Lease Term will
commence on the VAD Space Commencement Date, as defined below,
and will end on the last day of the Lease Term.

          a.   Cancellation Option. Paragraph II.B.(1)
(Acquisition Event Option) of the Original Lease, as amended by
the First and Second Amendments, shall apply to the VAD Space.

               Paragraph II.B(2) and (3) of the Lease shall not
apply to the VAD Space.

               The third paragraph of Paragraph 8 of the Second
     Amendment shall not apply to the VAD Space.

               In addition to Tenant's rights under Paragraph
     II.B of the Lease as amended hereunder, Tenant shall have
     the right to terminate this Lease with respect to the VAD
     Space  only (for purposes of this Paragraph 7 only,
     termination of the Lease shall be deemed to be termination
     of the Lease with respect to the VAD Space only) at any time
     from and after June 30, 1998 through and including November
     30, 2001, upon at least six (6) months' prior written notice
     to Landlord, which notice may be delivered to Landlord at
     any time from and after December 30, 1997 through and
     including May 30, 2001. If Tenant exercises its right to
     terminate this Lease under this Paragraph 7, Tenant shall
     pay Landlord by certified or bank cashier's check made
     payable to Landlord, or at Landlord's option, by wire
     transfer of immediately available funds to Landlord's
     account, on or before the month immediately preceding the
     proposed date of Lease termination in Tenant's notice, a fee
     (the "Fee") of Ninety Thousand Dollars ($ 90,000.00) and as
     of the Lease termination date hereunder, Tenant shall have
     cured any uncured monetary default under the Lease,
     including any late fees due thereon, without any obligation
     to pay any accelerated Rent.  Notwithstanding the
     immediately preceding sentence, the Fee shall be reduced by
     One Thousand Seven Hundred Dollars ($1,700.00) per month
     commencing on June 30, 1998. If Tenant's termination of the
     Lease under this Paragraph is effective on November 30,
     2001, Tenant shall owe no Fee upon termination of the Lease
     hereunder.

               The fourth paragraph of Paragraph 8 of the Second
Amendment shall apply to the VAD Space and shall be amended by
striking the first sentence thereof and substituting the
following:

          "Landlord shall provide to the Tenant not later
      than thirty (30) days before (a) the last day of the
      Second Expansion Space Lease Term pursuant to
      Tenant's notice of termination under this Paragraph
      (the "Second Expansion Space Termination Date"); or
      (b) the date of termination of the Lease set forth in
      Tenant's notice to Landlord with respect to the VAD
      Space (the "VAD Space Termination Date") (the term
      "Termination Date" shall refer to the VAD Space or
      Second Expansion Space Termination Date, as
      applicable), a termination rent statement (the
      "Termination Rent Statement"), which Termination Rent
      Statement shall set forth through the Termination
      Date all then-uncured monetary defaults with respect
      to Basic Annual Rent, including any previously-billed
      and unpaid late fees due on any and all such late
      payments of Basic Annual Rent, and all Basic Annual
      Rent which is then unpaid or which will be payable
      under the Lease through and including the Termination
      Date."
      
           b.  VAD Space Commencement Dates.
 
                (i) The VAD Space Commencement Date for Phase I
 shall be the date that (i) Phase I of the VAD Space
 Construction, as shown on Exhibit A, is substantially complete,
 as certified to Tenant by Landlord's architect for the VAD
 Space Construction; (ii) Landlord has obtained a temporary
 certificate of occupancy and all other licenses and permits
 required with respect to construction-related issues only, for
 Phase I of the VAD Space Construction; and (iii) the lease
 between Landlord and VAD for the VAD Space has been terminated
 pursuant to a fully-executed Termination of Lease Agreement
 between VAD and Landlord.  (Landlord and Tenant agree that
 Landlord shall use best efforts to obtain such a Termination of
 Lease Agreement by no later than 6 p.m. on Friday, September
 13, 1996.) The VAD Space Commencement Date for Phase I shall be
 pushed back one (1) day for each day that the VAD Space
 Construction for Phase I is delayed due to (i) Tenant-generated
 change orders to the VAD Space Plans; (ii) delays of any nature
 whatsoever caused by Tenant; and/or (iii) Tenant negligence or
 willful misconduct. Landlord shall give Tenant written notice
 of the anticipated VAD Space Commencement Date for Phase I on
 or about seven (7) days before such Date. Upon the occurrence
 of the VAD Space Commencement Date for Phase I, Landlord and
 Tenant shall execute a written statement setting forth such
 Date.
 
                 (ii) The VAD Space Commencement Date for Phase
 II shall be the date that Phase II of the VAD Space
 Construction, as shown on Exhibit A, is substantially complete,
 as certified to Tenant by Landlord's architect for the VAD
 Space Construction, and the date that Landlord has obtained a
 final certificate of occupancy and all other licenses and
 permits required with respect to construction-related issues
 only, for Phase II of the VAD Space Construction. The VAD Space
 Commencement Date for Phase II shall be pushed back one (1) day
 for each day that the VAD Space Construction for Phase II is
 delayed due to (i) Tenant-generated change orders to the VAD
 Space Plans; (ii) delays of any nature whatsoever caused by
 Tenant; and/or (iii) Tenant negligence or wilful misconduct.
 Landlord shall give Tenant written notice of the anticipated
 VAD Space Commencement Date for Phase II on or about seven (7)
 days before such Date. Upon the occurrence of the VAD Space
 Commencement Date for Phase II, Landlord and Tenant shall
 execute a written statement setting forth such Date.
 
           c.  Possession of VAD Space.  This Fourth Amendment
 will remain fully effective and Tenant may not cancel or
 rescind it due to late possession, regardless of when
 possession is actually delivered. Moreover, in no event will
 Landlord be liable to Tenant for damages, if any, sustained by
 Tenant as a result of Landlord's delay in delivering the VAD
 Space, except damages sustained solely as a direct result of
 Landlord's gross negligence or willful misconduct.
 
           d.  Acceptance of VAD Space.  Upon Landlord's
 delivery of possession of the VAD Space to Tenant, Tenant will
 be deemed to have accepted the VAD Space, subject to Landlord's
 duties otherwise provided herein.
 
      8.  Basic Annual Rent for VAD Space.
 
           a.  Amount of Basic Annual Rent for VAD Space. Basic
 Annual Rent for the VAD Space shall equal One Hundred Forty-Six
 Thousand Fifty-One Dollars and Twenty-Five Cents ($146,051.25)
 per annum, payable in equal monthly installments of Twelve
 Thousand One Hundred Seventy Dollars and Ninety-Four Cents
 ($12,170.94); provided, however, that for the period from the
 VAD Space Commencement Date for Phase I through the VAD Space
 Commencement Date for Phase II, the applicable monthly
 installment of Basic Annual Rent shall equal Six Thousand
 Eighty-Five Dollars an Forty-Seven Cents ($6,085.47). Payment
 of the first monthly installment hereunder shall commence on
 the VAD Space Commencement Date for Phase I; provided that if
 payment commences on a date that is not the first day of a
 month, then payment shall be pro-rated for the  partial  first
 month  in  which  payment commences. Basic Annual Rent shall
 increase once annually on December 1, 1997 and on every
 December 1 thereafter during the Lease Term at a fixed rate of
 three percent (3%) per year.
 
           b.  Payment of Basic Annual Rent for VAD Space.  The
 above amounts of Basic Annual Rent for the VAD Space shall be
 paid at the time and in addition to the payment of Basic Annual
 Rent for the Leased Premises, and otherwise in the manner set
 forth in Article III.B of the Lease.
 
           c.  Security Deposit. There shall be no Security
 Deposit required hereunder for the VAD Space.
 
      9.   Adjustments to Square Footages and Percentages
 
           a.  Paragraph III.C(l)(c)  of the Lease shall be
 amended so that the term "Rentable Area of the Leased Premises"
 shall be deemed to be Sixty-Nine Thousand Five Hundred Nine
 (69,509) square feet rather than Fifty-Eight Thousand Fifty-
 Four (58,054) square feet so that the term includes the VAD
 Space.  This amended square footage number shall apply
 throughout the Lease to all references to the square footage of
 the Leased Premises.   However, the  second  through  final
 sentences  of  Paragraph III.C(l)(c) of the Lease, as amended
 by this Fourth Amendment, shall not apply to the VAD Space.
 There shall be no certification required of the gross Rentable
 Area of the VAD Space.
 
           b.  Paragraph III.C(l)(e) of the Lease shall be
 amended as of the VAD Space Commencement Date so that the term
 "Tenant's Portion (with respect  to  the  payment  of  Common
 Area Expenses,  Taxes  and Insurance)" will be Fifty and Sixty-
 Five One Hundredths Percent  (50.65%) rather  than Forty-Two
 and Thirty-One One Hundredths Percent (42.31%), so that the
 term includes the VAD Space. This amended Tenant's Portion
 shall apply throughout the Lease.
 
           c.  The estimated amounts set forth in Paragraph
 III.C(2) (a) and (b) of the Lease shall be amended as of the
 VAD Space Commencement Date by  adding  thereto the  estimated
 amounts  of  such Taxes, Insurance  and  Common  Area  Expenses
 for  the VAD  Space. Therefore,  commencing  on the VAD Space
 Commencement Date, Tenant  shall  pay  to Landlord,  in
 addition to the amounts set  forth  in the Lease sections
 listed above, with and at the same time as the monthly payments
 of Basic Annual Rent, the following amounts with respect to the
 VAD Space:
 
                (i)   One Thousand Twenty-One Dollars and Forty
 Cents  ($1,021.40) per  month  as  one-twelfth  of  Tenant's
 estimated Portion of Common Area Expenses, which amount
 includes One Hundred Forty-Three Dollars and Nineteen Cents
 ($143.19) per month as one-twelfth of Tenant's estimated
 Portion of the Insurance Costs.  The limitation on increases in
 Common Area Expenses under the Lease shall apply to Tenant's
 Portion of Common Area Expenses for the VAD Space, except that
 the Common Area Expenses for the VAD Space for the first Lease
 Year shall not be limited in any way.
 
                (ii)   One Thousand Four Hundred Forty-One
 Dollars and Forty-Two Cents ($1,441.42) per month as
 one-twelfth of Tenant's estimated Portion of Taxes.
 
      10. Use Restrictions and Rules. Paragraph IV.A of the
 Original Lease shall apply to the VAD Space.
 
      11. Improvements by Tenant.  Subsection (i) of the second
 paragraph of Paragraph IV.B of the Lease shall be stricken in
 its entirety and replaced with the following:
 
           "(i)  the aggregate cost of the same does not exceed
           One Hundred Thousand Dollars ($100,000) with respect
           to the Expanded Leased Premises, Fifty Thousand
           Dollars ($50,000) with respect to the Second
           Expansion Space, or Fifty Thousand Dollars ($50,000)
           with respect to the VAD Space . . ."
 
      12. Insurance.  Paragraph IV.E of the Original Lease and
 shall apply to the VAD Space.
 
      13. Damage and Destruction.  Article VI of the Lease shall
 be amended by adding the underlined language to the last
 paragraph thereof and adding a new paragraph at the end thereof
 as follows:
 
           Notwithstanding the preceding three (3) paragraphs of
 this Article VI, if Landlord or Tenant has the right to
 terminate the Lease pursuant to this Article VI due to damage
 or destruction to the Expanded Leased Premises only (excluding
 the Second Expansion Space and VAD Space) by fire, other
 casualty, or any other cause (except condemnation), then
 Landlord or Tenant automatically shall have the right pursuant
 to this Article VI to terminate the Lease with respect to the
 Second Expansion Space and VAD Space, regardless of whether the
 Second Expansion Space and/or the VAD Space has suffered any
 damage or destruction.  In addition to the termination rights
 with respect to the Second Expansion Space and VAD Space in the
 immediately preceding sentence, Tenant shall have the right to
 terminate the Lease with respect to the Second Expansion Space
 and VAD Space within one (1) year of the date of damage or
 destruction to the Expanded Leased Premises, upon thirty (30)
 days' prior written notice to Landlord. In the event of such
 termination, the same conditions shall apply as are set forth
 in Article VI. If Landlord or Tenant has the right to terminate
 the Lease pursuant to this Article VI due to damage or
 destruction to the Second Expansion Space and/or VAD Space only
 (excluding the Expanded Leased Premises), Landlord or Tenant
 shall not have any right to terminate the Lease with respect to
 the Expanded Leased Premises. If Landlord or Tenant duly
 terminates the Lease under Article VI with respect to the
 Second Expansion Space and/or VAD Space, the Lease shall remain
 in full force and effect with respect to the Expanded Leased
 Premises, and the Second Expansion Space and/or VAD Space shall
 be stricken from the definition of "Leased Premises" under the
 Lease.  Upon such damage or destruction to the Second Expansion
 Space and/or the VAD Space, the parties agree to enter into an
 amendment to the Lease setting forth the reduced Leased
 Premises and other related changes to the Lease, including,
 without limitation, reduction of Basic Annual Rent and Tenant's
 Portion of Common Area Expenses, Taxes and Insurance.
 
           Notwithstanding anything set forth above in this
 Article VI, if Landlord or Tenant has the right to terminate
 the Lease pursuant to this Article VI due to damage or
 destruction to one or the other of the Second Expansion Space
 or the VAD Space, but not both Spaces, then Landlord or Tenant
 shall not have the right to terminate the Lease under this
 provision with respect to the non-damaged Space in Building B,
 or with respect to the Expanded Leased Premises.
 
      14. Condemnation.  The last sentence of the second
 paragraph of Article VII of the Lease shall only apply to the
 Expanded Leased Premises, and shall not apply to the Second
 Expansion Space and VAD Space.  In addition, Article VII of the
 Lease shall be amended by adding the underlined language to the
 last paragraph thereof and adding a new paragraph at the end
 thereof as follows:
 
           Notwithstanding the preceding two (2) paragraphs of
 this Article VII, if Landlord or Tenant has the right to
 terminate the Lease pursuant to this Article VII due to taking
 or condemnation of the Expanded Leased Premises only
 (excluding the Second Expansion Space and VAD Space), then
 Landlord or Tenant automatically shall have the right pursuant
 to this Article VII to terminate the Lease with respect to the
 Second Expansion Space and VAD Space, regardless of whether the
 Second Expansion Space and/or the VAD Space has been condemned
 in whole or in part.  However, if Landlord or Tenant has any
 right to terminate the Lease pursuant to this Article VII due
 to condemnation or taking of the Second Expansion Space and/or
 VAD Space only (excluding the Expanded Leased Premises),
 Landlord or Tenant shall not have the right to terminate the
 Lease with respect to the Expanded Leased Premises. If Landlord
 or Tenant duly terminates the Lease under Article VII with
 respect to the Second Expansion Space and/or VAD Space, the
 Lease shall remain in full force and effect with respect to the
 Expanded Leased Premises, and the Second Expansion Space and/or
 VAD Space shall be stricken from the definition of "Leased
 Premises" under the Lease.  Upon such condemnation of the
 Second Expansion Space and/or VAD Space, the parties agree to
 enter into an amendment to the Lease setting forth the reduced
 Leased Premises and other related changes to the Lease,
 including, without limitation, a reduction of Basic Annual Rent
 and Tenant's Portion of Common Area Expenses, Taxes and
 Insurance.
 
           Notwithstanding anything set forth above in this
 Article VII, if Landlord or Tenant has the right to terminate
 the Lease pursuant to this Article VII due to taking or
 condemnation of one or the other of the Second Expansion Space
 or the VAD Space, but not both Spaces, then Landlord or Tenant
 shall not have the right to terminate the Lease under this
 provision with respect to the non-condemned Space in Building
 B, or with respect to the Expanded Leased Premises.
 
      15. Parking. Paragraph X.O of the Lease shall be amended
 by adding Tenant's right to the non-exclusive use of an
 additional three (3) parking spaces per one thousand (1,000)
 square feet of the VAD Space for a total of Thirty-Four (34)
 parking spaces. Therefore, in addition to the 214 non-exclusive
 and 15 exclusive parking spaces set forth in the Lease, Tenant
 shall have the non-exclusive use of 34 additional parking
 spaces in the front and rear of Building B. If Tenant's loading
 requirements or other requirements in the rear of Building B
 are such that there is room for additional parking, then Tenant
 shall have the non-exclusive use of additional parking spaces
 in the rear of Building B.
 
      16. Rights of First Offer. The provisions of Paragraph 18
 of the First Amendment shall be amended to the extent, and only
 to the extent, set forth below:
 
           a.  (i) Tenant shall have the right of first offer
 (the "Hitachi First Offer Right"), on the terms and conditions
 hereinafter set forth, to lease that portion of Building B
 contiguous to the VAD Space (the "Hitachi First Offer Space"),
 as shown on Exhibit A, containing approximately Three Thousand
 Three Hundred Seventy (3,370) rentable square feet, and as of
 the date first set forth above, occupied by Nissei Sangyo
 America, Ltd. ("Hitachi") under a lease between Landlord and
 Hitachi (the "Hitachi Lease") at such time as such Space
 becomes available after its initial leasing by Hitachi. Tenant
 shall have the right to lease the Hitachi First Offer Space at
 the then-current VAD Space Basic Annual Rent, with a tenant
 improvement allowance of Seven Dollars and Fifty Cents ($7.50)
 per square foot.
 
                (ii) Tenant shall have the right of first offer
 (the "Bodymasters First Offer Right"), on the terms and
 conditions hereinafter set forth, to lease that portion of
 Building B contiguous to the VAD Space (the "Bodymasters First
 Offer Space"), as shown on Exhibit A, containing approximately
 Ten Thousand Seventy-Three (10,073) rentable square feet,  and
 occupied as of the Effective Date by Healthco Fitness
 ("Bodymasters") under a lease between Landlord and Bodymasters
 (the "Bodymasters Lease"). Tenant shall have the Bodymasters
 First Offer Right at such time as the Bodymasters First Offer
 Space becomes available, subject to any renewal options in the
 Bodymasters Lease. Tenant shall have the right to lease the
 Bodymasters First Offer Space at the then-current market rent
 (as determined below), including, without limitation, then-
 current market increases of basic annual rent for each lease
 year of such lease. Market rent shall be determined based, in
 part, upon a tenant improvement allowance for the Bodymasters
 First Offer Space agreed upon by Landlord and Tenant.
 
           Landlord and Tenant shall work together in good faith
 to determine market rent for the Bodymasters First Offer Space,
 based on the mutually-agreed tenant improvement allowance,
 within ten (10) days after Landlord receives Tenant's First
 Offer Notice (as defined below). However, if Landlord and
 Tenant cannot agree on a market rent within such ten (10)-day
 period, after diligent, good faith efforts, then market rent
 for the Bodymasters First Offer Space, taking into
 consideration the tenant improvement allowance established by
 Landlord and Tenant, shall be determined by a three-broker
 method conducted as follows:
 
                     (1) Within five (5) days after Landlord and
 Tenant shall have failed to agree upon a market rent during the
 ten (10)-day period set forth above, Landlord and Tenant shall
 give written notice to the other that each, at its own expense,
 has hired and appointed as a broker, a disinterested person of
 recognized competence and professional experience as a broker
 of comparable commercial and industrial real estate in the
 Baltimore-Washington Metropolitan Area. The two (2) brokers
 thus appointed shall diligently work together for fifteen (15)
 days after their appointment to determine the market rent for
 the Bodymasters First Offer Space. Landlord and Tenant shall
 each be entitled to present evidence and argument to the two
 (2) brokers. If the two brokers cannot agree on such a market
 rent within such fifteen (15)-day period, they shall each
 prepare a written report setting forth what each believes the
 market rent to be and the supporting data therefor. They shall
 then appoint a third broker who shall also be a disinterested
 person of recognized competence and professional experience as
 a broker of comparable commercial and industrial real estate in
 the Baltimore-Washington Metropolitan Area (the "Broker").  In
 the event that the two (2) brokers appointed as aforesaid shall
 be unable to agree, within ten (10) days after their failure to
 agree on a market rent, on the appointment of the Broker, they
 shall give written notice of such failure to the parties
 hereto, and the parties shall request that such appointment be
 made by the then President of the Maryland/Washington, D.C.
 Chapter of the Society of Industrial and Office Realtors (or
 any organized successor thereto) within thirty (30) days after
 such request. The Broker shall, as promptly as possible, but in
 no event more than thirty (30) days after the date of his or
 her selection, determine the market rent for the Bodymasters
 First Offer Space, without having access to the reports of the
 first two (2) brokers. Landlord and Tenant shall each be
 entitled to present evidence and argument to the Broker. Once
 the Broker has determined the market rent, the final market
 rent shall be determined as follows: (a) if the Broker's
 determination is higher than that of both of the first two
 brokers, then the higher market rent as determined by the first
 two brokers shall be conclusive and binding on Landlord and
 Tenant; (b) if the Broker's determination is lower than that of
 both of the first two brokers, then the lower market rent as
 determined by the first two brokers shall be conclusive and
 binding on Landlord and Tenant; and (c) if the Broker's
 determination is between that of the first two brokers, then
 the Broker's determination shall be conclusive and binding on
 Landlord and Tenant.
 
                     (2) After the market rent has been
 determined by the two (2) brokers, or determined by the method
 involving the Broker, as applicable, written notice shall
 immediately be given to Landlord and Tenant stating the
 determination(s), and Landlord and Tenant shall be furnished a
 copy of such determination(s) signed by the decision-maker(s).
 If the Broker is utilized, Landlord and Tenant shall review all
 three (3) determinations to arrive at the final market rent
 pursuant to the method set forth above. Landlord and Tenant
 shall each pay one-half (1/2) of the costs of the Broker, if
 applicable.
 
                (iii)  Tenant shall  exercise either of or both
 its First Offer Rights only upon written notification to
 Landlord of Tenant's exercise of any such First Offer Right
 (the "First Offer Notice"). Such First Offer Notice must be
 given to Landlord within five (5) business days after Tenant
 receives Landlord's written notification to Tenant ("Landlord's
 Offer") of the termination of the Hitachi and/or Bodymasters
 Lease, as applicable.
 
                (iv)  Time is of the essence with respect to
 Tenant's exercise of its rights under this Subparagraph, and
 Tenant acknowledges that Landlord requires strict adherence to
 the requirement that the applicable First Offer Notice be
 timely made and in writing. Within ten (10) days after the
 market rent for the Bodymasters First Offer Space has been
 determined as provided above, Tenant shall have the right, by
 written notice to Landlord, to rescind its exercise of its
 Bodymasters First Officer Notice, as applicable.
 
                (v)  In the event Tenant fails to provide
 Landlord with the applicable First Offer Notice within the five
 (5) day period set forth in Subparagraph 16(a)(iii) above,
 Landlord shall be free to offer said Hitachi or Bodymasters
 First Offer Space to a third party on any terms whatsoever, and
 the applicable First Offer Right shall be null and void and of
 no further force and effect.
 
                (vi)  In the event that either one or both of
 the First Offer Rights are exercised by Tenant, the rent
 applicable to the applicable First Offer Space as set forth
 above in this Paragraph 16, shall be payable in equal monthly
 installments (and, where applicable, fractions thereof), at the
 times and in the manner as provided with respect to, and in
 addition to, the monthly installments of the Basic Annual Rent
 as set forth in Article III.B. of the Lease.
 
           b.  Notwithstanding any other provision of this
 Paragraph 16, the following provisions shall apply to the First
 Offer Rights and to Tenant's lease, if any, of the applicable
 First Offer Space.
 
                (i)  Tenant shall not be entitled to exercise
 the rights accorded to Tenant in Subparagraph 16(a), unless on
 the date Tenant gives Landlord notice of such exercise and on
 the applicable First Offer Space Commencement Date, as
 hereinafter defined, Tenant (for purposes of this subsection
 only, the term "Tenant" shall be deemed to be MedImmune, Inc.
 or an entity which succeeds to all or substantially all of the
 assets of MedImmune, Inc.) is in possession of the Leased
 Premises and Tenant is not in default of the Lease;
 
                (ii)  The lease by Tenant of the applicable
 First Offer Space, if any, shall commence on the date set forth
 in Landlord's Offer (the "Hitachi First Offer Space
 Commencement Date" or the "Bodymasters First Offer Space
 Commencement Date") and shall terminate on November 30, 2006,
 under and subject to the terms of this Lease (except to the
 extent modified by Landlord's Offer), with the same force and
 effect as though this Lease had originally provided for the
 rental of the Leased Premises and the applicable First Offer
 Space, except that the Basic Annual Rent applicable to the
 applicable First Offer Space shall be adjusted as set forth
 above. Notwithstanding the immediately preceding sentence,
 Tenant shall have the right to cancel the lease for the Hitachi
 First Offer Space and/or the lease for the Bodymasters First
 Offer Space on November 30, 2001 upon at least one hundred
 eighty (180) days' prior written notice. Tenant shall owe a
 penalty for canceling the leases for the Hitachi First Offer
 Space and for the Bodymasters First Offer Space equal to, with
 respect to each such lease, the unamortized portion of the
 applicable tenant improvement costs and commissions, plus an
 amount equal to three (3) months' basic annual rent then in
 effect. The tenant improvement costs under the leases for both
 the Hitachi and Bodymasters First Offer Spaces shall be
 amortized at ten and one half percent (10.5%) per annum (pro-
 rated on a monthly basis) over the term of each of the leases
 for the Bodymasters and Hitachi First Offer Space, as
 applicable. Landlord shall apply this formula to determine the
 Bodymasters and Hitachi cancellation penalties hereunder upon
 receipt of the applicable Tenant's First Offer Notice
 hereunder, and shall notify Tenant in writing of the amount of
 each such cancellation fee, and the calculations used to
 determine it, within seven (7) days of receipt of the
 applicable Tenant's First Offer Notice. If Tenant has any
 questions or concerns about such calculations, Tenant shall
 notify Landlord in writing within seven (7) days of receipt of
 Landlord's calculations, and the parties shall use diligent,
 good faith efforts to resolve all open issues promptly.
 
                (iii)  The applicable First Offer Space shall be
 delivered to Tenant in "as is" condition, unless otherwise set
 forth in Landlord's Offer.
 
                (iv)  From and after the applicable First Offer
 Space Commencement Date, all references in the Lease to the
 Leased Premises shall refer to both the area of the Leased
 Premises and of the applicable First Offer Space. Tenant's
 Portion shall be adjusted accordingly to reflect the leasing of
 the applicable First Offer Space.
 
                (v)  Except as otherwise expressly provided in
 this Paragraph 16, and after the applicable First Offer Space
 Commencement Date, all of the covenants and agreements set
 forth in the Lease, schedules and riders thereto shall apply to
 the applicable First Offer Space.
 
      17. Signage for the VAD Space. Paragraph 18 of the Second
 Amendment shall be stricken in its entirety and replaced with
 the following:
      
                "As soon as reasonably possible after Landlord
           and Tenant have approved of the location of Tenant's
           signage, and as otherwise set forth below in this
           Paragraph 17, Landlord shall construct, maintain,
           repair and/or replace for Tenant exterior signage on
           Building B displaying Tenant's name, logo, and/or any
           other insignia generally used by Tenant. All costs
           associated with maintenance, repair and replacement
           of this exterior signage shall be treated as a Common
           Area Expense. Tenant shall pay all costs associated
           with the construction of such signage within thirty
           (30) days of receipt of an invoice therefor from
           Landlord. This signage shall be of identical size,
           color and material as the size, color and material
           used for similar signage on Building D, and this
           signage on Building B shall be in such location as is
           reasonably requested by Tenant and approved in
           advance by Landlord, in Landlord's sole discretion."
 
      18. Tenant  Authorization.    Tenant  represents  and
 warrants to Landlord that this Fourth Amendment has been
 validly authorized and is executed by an authorized officer of
 Tenant and that its terms are binding upon and enforceable
 against Tenant in accordance herewith.
 
      19. Amendment. As of and after the date hereof, the Lease
 shall be amended and in full force and effect in such respects
 as are set forth in this Fourth Amendment, and all other
 provisions, terms, conditions and riders of and to the Lease
 shall in all respects remain in full force and effect as set
 forth in the Lease.
 
      20. Reaffirmation. Tenant hereby reaffirms and restates,
 and agrees to be bound by, the covenants, promises,
 representations and agreements set forth in the Lease (except
 to the extent that they are expressly superseded by this Fourth
 Amendment) as if made herein.
 
      21. Authority. Tenant represents and warrants to Landlord
 that the Lease and this Fourth Amendment were approved by all
 necessary parties, were validly executed by all necessary
 officers of Tenant, and are and remain binding upon and
 enforceable against Tenant in accordance with their terms, and
 that the name and address of Tenant's resident agent in the
 State of Maryland are The Corporation Trust Incorporated, 32
 South Street, Baltimore, Maryland 21202.
 
      IN WITNESS WHEREOF, Landlord and Tenant have respectively
 signed this Fourth Amendment of Lease under seal as of the day
 and year first above written, intending to be bound as of the
 Effective Date.
 
 WITNESS/ATTEST:              CLOPPER ROAD ASSOCIATES
 
                               By: M.O.R.M. Associates Limited
                                    Partnership
 
                                    By: RA & FM, Inc.
 
                              By:  Alton D. Fryer(SEAL)
                                    Name: Alton D. Fryer
                                    Title: Vice President
 LANDLORD
 
 WITNESS/ATTEST:              MEDIMMUNE, INC.
 
 David LeBuhn                 By:  David M. Mott(SEAL)
                               Name:  David M. Mott
                               Title:  President
                                                   TENANT
 
 STATE OF MARYLAND            )
                               )   TO WIT:
 COUNTY OF FREDERICK          )
 
      I HEREBY CERTIFY that on this 4th day of October, 1996,
 before me, the subscriber, a Notary Public of the State of
 Maryland and County/City of Baltimore, personally appeared
 before me Alton D. Fryer, Vice President, of RA & FM, Inc., a
 general partner of M.O.R.M. Associates Limited Partnership, a
 general partner of CLOPPER ROAD ASSOCIATES, Landlord, and s/he
 acknowledged the foregoing Fourth Amendment of Lease to be the
 act and deed of said joint venture.
 
      WITNESS my hand and notarial seal.
 
                                    Mary Gail Peters
                                    Notary Public
 
 My Commission Expires:  April 1, 1998
                                    [Notaries cont'd]
                                    
 
 
 STATE OF MARYLAND            )
                               )   TO WIT:
 COUNTY/CITY OF MONTGOMERY    )
 
      I HEREBY CERTIFY that on this 3rd  day of October 1996,
 before me, the subscriber, a Notary Public of the State of
 Maryland and County/City of Montgomery, personally appeared
 before me David M. Mott, who acknowledged her/himself to be the
 President and Chief Operating Officer of MEDIMMUNE, INC.,
 Tenant and she/he acknowledged the foregoing Fourth Amendment
 of Lease to be the act and deed of said corporation.
 
      WITNESS my hand and notarial seal.
 
                                    Carol A. Iorio
                                    Notary Public
 
 My Commission Expires: July 11, 1998
                                
                            EXHIBIT A
                    Description of VAD Space
                                
                                
                            EXHIBIT B
                         VAD Space Plans