BIOGEN, INC.

                  1983 EMPLOYEE STOCK PURCHASE PLAN
         (as amended through September 22, 1995 and restated)

I. Purpose and Definitions

     A.  Purpose of the Plan:  The Plan is intended to encourage
ownership of Shares by all employees of the Company and its
Affiliates, as hereinafter defined.

     B.  Definitions:  Unless otherwise specified or unless the
context otherwise requires, the following terms, as used in this
Employee Stock Purchase Plan, have the following meanings:

     1.  "Affiliate" means a corporation which is a direct or
     indirect fifty percent (50%) or more owned parent or
     subsidiary of the Company.

     2.  "Board" means the Board of Directors of the Company.

     3.  "Code" means the United States Internal Revenue Code of
     1986, as amended.

     4.  "Committee" means the Company's Stock and Option Plan
     Administration Committee to which the Board of Directors has
     delegated power to act under and pursuant to the provisions of
     this Plan.

     5.  "Company" means Biogen, Inc., a Massachusetts Corporation.

     6.  "Compensation" means salary and wages, including overtime
     pay, received  by an employee before any salary reduction by
     the employee under Code Sections 401(k) or 125, but excluding
     bonus, incentive and similar payments and all other forms of
     non-cash remuneration.

     7.  "Employee" means any individual who performs services for
     the Company or its Affiliates pursuant to an employment
     relationship other than those persons whose customary
     employment is 20 hours or less per week, excluding employees
     of non-U.S. Affiliates of the Company, except as is otherwise
     determined by the Committee.

     8.  "Enrollment Dates" are the earliest date participation is
     permitted hereunder by the Committee when the Plan is first
     made operative and each successive January 1 and July 1
     thereafter.

     9.  "Fair Market Value"

          (i)  If Shares are purchased by the Plan on a U.S.
          securities exchange, the actual purchase price of such
          Shares shall be such Shares' Fair Market Value. 

          (ii)  In all other circumstances including if Shares are
          purchased by the Plan from the Company, in determining
          such Shares' Fair Market Value, if such Shares are then
          listed on any U.S. securities exchange, or the National
          Association of Securities Dealers Automated Quotation
          System ("NASDAQ") National Market System, the Fair Market
          Value shall be the average between the high and low sale
          prices, if any, on the largest such exchange or on the
          NASDAQ National Market System, as the case may be, on the
          applicable date, or, if none, on the most recent trade
          date thirty (30) days or less prior to such date.  If the
          Shares are not then listed on any such exchange or on the
          NASDAQ National Market System, the Fair Market Value of
          such Shares shall be the average of the closing "Bid" and
          the closing "Ask" prices, if any, as reported in NASDAQ
          for such date, or if none, on the most recent trade date
          thirty (30) days or less prior to such date for which
          such quotations are reported.  If the Fair Market Value
          cannot be determined under the preceding two sentences,
          it shall be determined in good faith by the Committee.

     10.  "Option" means a right or option granted under the Plan.

     11.  "Participant" means an Employee who is enrolled in the
     Plan, provided however that no Employee may be granted an
     Option under this Plan if, immediately after the Option is
     granted, such Employee owns stock possessing five percent (5%)
     or more of the total combined voting power, (or in the case of
     non-voting stock, value) of all classes of issued and
     outstanding stock of the Company or Affiliate(s) (other than
     wholly owned subsidiaries of the Company.)  For purposes of
     determining stock ownership the applicable rules of the Code
     (including attribution) shall control.

     12.  "Participant's Survivors" means a deceased Participant's
     legal representatives and/or any person or persons who
     acquired the Participant's rights to an Option by will or by
     the laws of descent and distribution including where
     appropriate his/her estate.

     13.  "Plan" means this Employee Stock Purchase Plan.

     14.  "Shares" means the Common Stock, $.01 par value, of the
     Company as to which Options have been or may be granted under
     the Plan or any shares of capital stock into which the Shares
     are changed or for which they are exchanged within the
     provisions of Article VI of the Plan. 

II.  Shares Subject to the Plan

     A.  Subject to the terms of Article VI the maximum aggregate
number of Shares which may be optioned and purchased from time to
time shall be Two Hundred Fifty Thousand (250,000) Shares.

     If  an Option ceases to be "outstanding", in whole or in part,
the Shares which were subject to such Option but not purchased
shall be available for the granting of the other Options.  An
Option shall be treated as "outstanding" until such Option is
exercised in full, or terminates or expires under the provisions of
the Plan.

     B.  No options shall be granted after December 31, 1997.

III.  Administration of the Plan

     The Plan shall be administered by the Committee.  Subject to
the provisions of the Plan, the Committee is authorized to
interpret the provisions of the Plan and each Option, and to make
any rules and determinations which it deems necessary or advisable
for the administration of the Plan provided, however, that all such
interpretations, rules, determinations, terms and conditions shall
be made and prescribed in the context of preserving the tax status
of the Options under the Plan granted to Employees subject to
United States Federal Income Taxation, and the Plan itself within
the Meaning of Section 423 of the Code.  In addition, the Plan is
intended to comply in all respects with Rule 16b-3 or its
successors promulgated under the Securities Exchange Act of 1934,
as amended ("1934 Act"), with respect to participants who are
subject to Section 16 of the 1934 Act.  The Plan will be
interpreted in a manner which comports with this intention.

IV.  Eligibility for Participation

     A.  Subject to the limits in Article II, on the January 1
Enrollment Date of each year in the case of an Employee who is a
Participant on such January 1 Enrollment Date and on the July 1
Enrollment Date of each year in the case of an Employee who is a
Participant on such July 1 Enrollment Date, the Company will be
deemed to have granted to each such Participant an Option to
purchase, during a six-month period commencing on the Enrollment
Date on which such Option is granted and in the manner provided
hereunder, such number of Shares as have an aggregate Employee
Share Price (as determined under Article V(A)) equal to $2,500. 
If, on any Enrollment Date, an insufficient number of Shares
remains available under the Plan to grant to each Participant an
Option to purchase such number of Shares, then the number of Shares
subject to each Option to be granted on such Enrollment Date shall
be reduced equally so that the aggregate number of Share subject to
all Options granted on such Enrollment Date shall not exceed the
number of Shares then available under the Plan.

     B.  Employee Contributions:  Each eligible Employee may, on an
Enrollment Application and Payroll Withholding Form filed with
his/her employer's payroll department no later than thirty (30)
days prior to a January or July Enrollment Date (and with respect
to the Plan's first enrollment date specified at Article 1(B)(8),
no later than five days prior to such first Enrollment Date), elect
to participate and make contributions by payroll deduction of any
whole percentage form 1% to 10% of such Employee's Compensation
payable on each payroll period.

     In the event that the amount contributed by a Participant
during an Option exercise period (i.e., the six-month periods
commencing on an Enrollment Date) is in excess of the maximum
amount which may be applied to purchase shares for such
Participant, such excess shall be reimbursed to the Participant. 
No interest shall accrue or be payable to any Participant in the
Plan with respect to any amount contributed by the Participant,
whether such sums are applied to purchase Shares or are returned to
the Participant.

     Payroll deductions may only be increased by a Participant
effective as of  an Enrollment Date, but may be decreased effective
with respect to any payroll period, provided written election on a
Change Authorization and Payroll Withholding Form is received by
the Participant's employer's payroll department no later than
thirty (30) days prior thereto.

     C.  Application of Payroll Contributions:

          1.  The employer will remit to a bank, stock brokerage
     firm or other custodian (the "Custodian") selected by the
     Company, the accumulated withheld funds of all electing
     Participants together with employer contributions pursuant to
     Article IV(G), if any, as soon as reasonably possible
     following the end of the month in which the deductions were
     made.  Prior to such remittance, Participant contributions may
     be commingled with other Company funds.  Not less frequently
     than monthly, the Custodian shall buy from the Company or, if
     the Committee prior thereto approves, give an order to the
     stock broker selected by the Company to purchase (or if the
     Custodian shall be such stock broker, shall itself purchase)
     in the open market, the total number of Shares purchasable
     with the monies available from such remittance.  The date on
     which Shares are so acquired shall be referred to as the
     "Monthly Share Purchase Date."  The Committee shall instruct
     the Custodian whether to purchase Shares from the Company or
     on the open market, after giving due consideration to any
     applicable securities laws and the advice of the chief
     financial officer of the Company.  A Participant shall be
     deemed to have exercised his/her Options on the Monthly Share
     Purchase Date to the extent of such purchase unless prior
     thereto the Participant shall have effectively withdrawn
     pursuant to the terms hereof.

          The Company may, in its sole and absolute discretion,
     refuse to sell Shares to the Custodian under the Plan if to do
     so would be violative of any commitment or restriction
     (whether legally binding or otherwise) not to issue or sell
     its own shares, as from time to time exists, and whether such
     commitment or restriction existed prior to or subsequent to
     the adoption of the Plan or for any other reason the Company
     deems appropriate.  The refusal of the Company to sell Shares
     to the Custodian under the Plan shall not adversely affect the
     Plan's right and power to acquire such Shares from any other
     source the Committee deems appropriate.

          2.   The certificates representing the Shares so
     purchased shall be issued in the name of and delivered to the
     Custodian and the account of electing Participant shall be
     credited with the number of Shares to which he/she shall be
     entitled on the basis of his/her proportion of the aggregate
     remittance.

          3.  Any cash dividends paid on Shares shall automatically
     be used to purchase additional shares of the Common Stock of
     the Company, unless a Participant in writing instructs the
     Custodian to the contrary.  The purchases described in the
     preceding sentence, whether purchased by the Custodian from
     the Company or in the open market, shall be in addition to the
     number of Shares purchasable pursuant to Article II(A) and
     Article IV(A) and shall not be of Shares optioned under the
     Plan.  Article IV(G) with respect to employer's contribution
     shall be inapplicable with respect to shares of the Common
     Stock of the Company acquired under this Article IV(C) (3).

          4.  By enrolling in the Plan, each Participant is deemed
     to have authorized the establishment of a brokerage account in
     his/her name at a securities brokerage firm selected by or
     approved of by the Committee.

     D.  Transfer of Certificates to Electing Participants:

          1.  Upon request by a Participant and receipt by the
     Custodian of written notice to such effect from the Company,
     all or any portion of the Shares in the Participant's account
     shall be transferred by the Custodian out of its name into the
     name of the Participant and a certificate evidencing them
     shall be issued in the name of and delivered to such
     Participant.

          2.  In order to preserve the intended purposes of the
     Plan as set forth in Article 1(A) Employees who become
     Participants in the Plan agree not to transfer or otherwise
     dispose of Shares acquired on their behalf under the Plan
     (other than in the case of an Employee's death or total and
     permanent disability as determined by the Committee) prior to
     one year from the date of acquisition of such Shares on their
     behalf.

     E.  Shares Retained by the Custodian:  Accumulation of Shares
not transferred to Participants under Article IV(D) shall be held
by the Custodian for the account of the Participant entitled
thereto but all rights accruing to an owner of record on such
Shares shall belong to and be vested in the Participant for whose
account it is being held, including the right to receive any and
all dividend payable in respect of such Shares whether in cash,
shares of the Company's Common Stock or otherwise, and the right to
receive all notices of shareholders' meetings (which shall be
forwarded to the Participant by the Custodian without delay) and
direct the Custodian how to vote thereat to the same extent as if
such Shares were held in street name by a brokerage firm or
otherwise.

     F.  Withdrawal:

          1.  An electing Participant may discontinue his/her
     election and withdraw from the Plan as of the payroll period
     next following 30 days from the date written notice on a
     Change Authorization and Payroll Withholding Form  is received
     by his/her employer's payroll department; provided, however,
     that an electing Participant who shall have discontinued
     his/her election and withdrawn from the Plan may not
     resubscribe to the Plan prior to the Enrollment Date
     coincident with or next following twelve (12) months from the
     effective date of such discontinuance.

          2.  A Participant shall be deemed to have discontinued
     his/her election and withdrawn from the Plan immediately upon
     the occurrence of any of the following:

          a.  The termination for any reason of the Participant by
          the Company or an Affiliate.  A Participant's employment
          shall not be deemed terminated by reason of a transfer to
          another employer which is the Company or an Affiliate.  A
          Participant who has elected participation under the Plan
          who is absent from work with the Company or with an
          Affiliate because of temporary disability (any disability
          other than a permanent or total disability) or who is on
          leave of absence for any purpose authorized by his/her
          employer and permitted by an authoritative interpretation
          (e.g., regulation, ruling, case law, etc.) of Section 423
          of the Code, shall not, during the period of any such
          absence, be deemed, by virtue of such absence alone, to
          have terminated such Participant's employment with the
          Company or with an Affiliate, except as the Committee may
          otherwise expressly provide or determine.

          b.  Death of the Participant;

          c.  The filing with or levying upon the Company or the
          Custodian of any judgment, attachment, garnishment, or
          other court order affecting either the Participant's
          earnings or his/her account under the Plan;

          d.  Termination of the Plan prior to its expiration;

          e.  Expiration of the Plan.

          3.  Upon the discontinuance of an election and withdrawal
     from the Plan by a Participant, all Shares in the account of
     the Participant shall be transferred  out of the Custodian's
     name and into the name of the Participant and a certificate
     evidencing such Shares shall be issued in the name of and
     delivered to the Participant; and all dividends and remaining
     cash if any credited to his/her account shall be paid to the
     Participant.

     G.  Employer Contribution:  Each Participant's employer will,
as frequently as is necessary contribute an amount equal to the
difference between the Employee's Share Price as determined at
Article V(A) and the cost per share to the Custodian if the Shares
are not acquired from the Company.  If the Shares are acquired from
the Company, the Company shall sell such Shares to the Custodian at
a price equal to the Employee's Share Price determined pursuant to
Article V(A).

V.  Terms and Conditions of Options and Issuance of Shares

     No Option shall be granted to a Participant, and no purported
grant of any Option shall be effective, until an Enrollment
Application and Payroll Withholding Form shall have been duly
executed on behalf of the Company and by the Participant.  Such
Enrollment Application and Payroll Withholding Form and the
agreement constituted thereby shall be subject to at least the
following terms and conditions:

     A.  Employee's Share Price:  The "Employee's Share Price" as
of a Monthly Share Purchase Date as determined at Article IV (C)(1)
shall be eighty-five percent (85%) of the lower of the:

          1.  Fair Market Value of the Shares at the date of grant
     of the Option (i.e., the applicable January 1 or July 1
     Enrollment Date); or
     
          2.  Fair Market Value of the Shares at the Monthly Share
     Purchase Date.

     B.  Effect of Death and Participant's Survivors:  In the event
that a Participant to whom an Option has been granted ceases to be
an employee of the Company or of an Affiliate by reason of such
Participant's death, such Option to the extent exercisable but not
exercised on the date of death shall be deemed exercised by the
Participant's Survivors to the extent of any monies contributed by
the Participant and his/her employer prior to the Participant's
death.

     A Participant may determine that a designated person shall
become the Participant's Survivor either by selecting a joint
account (with a right of survivorship running to such designated
joint owner), or by so designating in his/her will or otherwise as
controlled under the applicable law with respect to testamentary
dispositions.  In the absence of a valid disposition the applicable
laws of descent and distribution shall control.  The Custodian may
require such proof and indemnification (documentary or otherwise)
as it deems necessary and appropriate before releasing any Shares
and/or funds in a Participant's account to a person other than the
Participant.

     C.  Assignability and Transferability of Options:  By its
terms, an Option granted to a Participant shall not be transferable
by the Participant otherwise than by will or by the laws of descent
and distribution or pursuant to a qualified domestic relations
order as interpreted under Rule 16b-3 promulgated under the 1934
Act, and shall be exercisable, during the Participant's lifetime,
only by such Participant.  Such Option shall not be assigned,
pledged or hypothecated in any way (whether by operation of law or
otherwise).  Any attempted transfer, assignment, pledge,
hypothecation or other disposition of any Option or of any rights
granted hereunder contrary to the provisions of this Article V(C)
shall be null and void.

     D.  All Participants to Have Equal Rights and Privileges:  All
Participants shall have equal rights and privileges under the Plan. 
The fact that the maximum number of Shares which may be acquired by
Participants bears a uniform relationship to compensation or is
limited by a maximum purchase restriction shall not be deemed to be
violative of the foregoing sentence.  

VI.  Adjustments upon Changes in Capitalization

     In the event that the outstanding shares of the Company's
Common Stock are changed into or exchanged for a different number
or kind of shares or other securities of the Company or of another
corporation by reason of any reorganization, merger, consolidation,
recapitalization, reclassification, change in par value, stock
split-up, combination of shares or dividend payable in capital
stock, or the like, appropriate adjustment shall be made in the
number and kind of Shares for the purchase of which Options may be
granted under the Plan and, in addition, appropriate adjustment to
prevent dilution or enlargement of the rights granted to or
available for Participants, shall be made in the number and kind of
Shares and in the Option price per Share subject to outstanding
Options so that each Option holder shall be in a position
equivalent to the position the Option holder would have been in had
the Option holder exercised the Options immediately prior to the
applicable event.  No such adjustment shall be made which shall,
within the meaning of the applicable provisions of the Code,
constitute such a modification, extension or renewal of an Option
as to cause it to be considered as the grant of a new Option.

VII.  Effect of Dissolution or Liquidation of the Company

     Upon the dissolution or liquidation of the Company other than
in connection with a transaction to which the preceding Article VI
is applicable, all Options granted hereunder shall terminate and
become null and void; provided, however, that if the rights of a
Participant or a Participant's Survivors hereunder have not
otherwise terminated and expired, the Participant or the
Participant's Survivors shall be deemed to have exercised such
Options to the extent of any monies contributed by the Participant
or his/her employer as of the date immediately prior to such
dissolution or liquidation.

VIII.  Termination of the Plan

     No Options shall be granted after December 31, 1997.  The Plan
may be terminated at an earlier date by vote of either the
stockholders or the Board.  The termination of the Plan shall not
affect any Options granted or Shares acquired prior to the
effective date of such termination.

IX.  Amendment of the Plan

     Except as provided in the following sentence, the Plan may be
amended by the stockholders, by the Board, or by the Committee,
including amendment of the Plan from time to time to designate
corporations whose employees may be offered Options under the Plan
from among a group consisting of the Company and any corporation
which is or becomes its parent or subsidiary.  Amendments
effecting:  (i) any increase in the aggregate number of Shares
which may be issued under the Plan (other than an increase merely
reflecting a change in capitalization such as stock dividend or
stock split) or (ii) changing the designation of corporations whose
employees may be offered options under the Plan, except
designations described in the preceding sentence, must be approved
by the stockholders within twelve (12) months after such amendment
is adopted by the Board or by the Committee or such amendment is
void ab initio.  In addition, if the scope of any amendment is such
as to require stockholder approval in order to comply with Rule
16b-3 under the 1934 Act, such amendment shall also require
approval by the stockholders.  No amendment shall affect any
Options theretofore granted or any Shares theretofore acquired by a
Participant, unless such amendment shall expressly so provide and
unless any Participant to whom an Option has been granted who would
be adversely affected by such amendment consents in writing
thereto.

X.  Employment Relationship

     Nothing herein contained shall be deemed to prevent the
Company or an Affiliate from terminating the employment of a
Participant, nor to prevent a Participant from terminating his/her
employment with the Company or an Affiliate.

XI.  Optionees Not Stockholders

     Neither the granting of an Option nor the deduction from
payroll shall constitute an Employee the owner of Shares covered by
an Option until such Shares have been purchased on his/her behalf
pursuant to Article IV.

XII.  Withholding Taxes

     Any taxes subject to withholding payable with respect to the
amounts to be paid to the Custodian pursuant to the provisions
hereof will be deducted by a Participant's employer from the
balance of the Participant's salary, and not reduce the amounts so
to be paid to the Custodian.

XIII.  Use of Funds by the Company

     The proceeds received by the Company from the sale of Shares
pursuant to Options granted under the Plan will be used for general
corporate purposes.

XIV.  Statement of Account

     Following each purchase of Shares on behalf of a Participant,
such Participant will receive from the Custodian a statement of
his/her account showing (i) the respective total amounts of
payments  (by the Participant and if applicable the employer) made
to the Custodian on behalf of such Participant under Article IV
(C)(1) hereof, (ii) the Participant's share of any cash dividends
and other cash distributions and  of the amount and proceeds of
sale of any other distributions or rights received by the
Custodian, (iii) the total cost of all Shares purchased by the
Custodian for the account of such Participant, (iv) such
Participant's share of any stock dividends on the Shares, and (v)
the number of shares delivered, or to be delivered, to such
Participant with respect to the period since the last statement.

XI.  Brokerage Commissions and Other Costs

     Brokerage commissions, if any, payable in connection with the
purchase of Shares hereunder (and shares acquired through dividend
reinvestment, if any) and transfer taxes payable in connection with
the delivery to Participants of Shares acquired hereunder (and
shares acquired through dividend reinvestment, if any) together
with the other costs and expenses incurred in administering the
Plan, including the fees and expenses of the Custodian, will be
borne by the Company and its affiliates.

XIV.  Effective Date

     This plan became effective on October 1, 1983.