Document:

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                                                                   EXHIBIT 10.27

                                  BIOGEN, INC.

                    VOLUNTARY BOARD OF DIRECTORS SAVINGS PLAN
               (As amended and restated through December 14, 2001)

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                                TABLE OF CONTENTS

                                                                            Page

ARTICLE 1 INTRODUCTION....................................................... 1
          1.1     Purpose and Effective Date................................. 1

ARTICLE 2 DEFINITIONS........................................................ 1
          2.1     Biogen..................................................... 1
          2.2     Board...................................................... 1
          2.3     Committee.................................................. 1
          2.4     Director................................................... 1
          2.5     Fees....................................................... 1
          2.6     Participant................................................ 1
          2.7     Plan....................................................... 1
          2.8     Retainer................................................... 1
          2.9     Savings Plan............................................... 1
          2.10    Plan Year.................................................. 1

ARTICLE 3 PARTICIPATION...................................................... 1
          3.1     Eligibility and Participation.............................. 1
          3.2     End of Participation....................................... 1

ARTICLE 4 SAVINGS DEPOSITS BY PARTICIPANTS................................... 2
          4.1     Savings Deposits........................................... 2

ARTICLE 5 PARTICIPANTS' ACCOUNTS............................................. 3
          5.1     Participant Accounts....................................... 3
          5.2     Vesting.................................................... 3

ARTICLE 6 DISTRIBUTIONS TO PARTICIPANT....................................... 3
          6.1     Distributions for Financial Hardship....................... 3
          6.1.A   In-Service Distribution(s) at a Time Specified
                  by Participant ............................................ 5
          6.2     Distribution Upon Death of a Participant................... 4
          6.3     Other Distributions........................................ 4
          6.4     Installment Distributions in Certain Cases................. 4

ARTICLE 7 MISCELLANEOUS...................................................... 5
          7.1     Amendment or Termination of Plan........................... 5
          7.2     Benefits Not Currently Funded.............................. 5
          7.3     No Assignment.............................................. 6
          7.4     Responsibilities and Authority of Committee................ 6
          7.5     Limitation on Rights Created by Plan....................... 6
          7.6     Tax Withholding............................................ 6
          7.7     Text Controls.............................................. 6
          7.8     Applicable State Law....................................... 6

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                                    ARTICLE 1
                                  INTRODUCTION

1.1    PURPOSE AND EFFECTIVE DATE. The purpose of this plan is to provide
members of the Board of Directors of Biogen with a tax-deferred savings
opportunity. This plan allows participants to defer all or a portion of their
directors' fees and retainer by so electing before such fees and retainer have
been earned. The effective date of this plan is October 1, 1994.

                                   ARTICLE 2
                                  DEFINITIONS

       This section contains definitions of terms used in the plan. Where the
context so requires, the masculine includes the feminine, the singular includes
the plural, and the plural includes the singular.

2.1    BIOGEN means Biogen, Inc., a Massachusetts corporation, or any successor
to all or the major portion of its assets or business which assumes the
obligations of Biogen, Inc. under this plan.

2.2    BOARD means the Board of Directors of Biogen.

2.3    COMMITTEE means the Savings Plan Committee constituted under the Savings
Plan.

2.4    DIRECTOR means an individual serving as a director of Biogen in
accordance with its articles and by-laws.

2.5    FEES means the amounts payable to a director as compensation for his or
her attendance at a meeting of the Board or a committee of the Board.

2.6    PARTICIPANT means a director who has made a savings deposit hereunder.

2.7    PLAN means the Biogen, Inc. Voluntary Board of Directors Savings Plan, as
set forth in this plan instrument, and as it may be amended from time to time.

2.8    RETAINER means the amount payable to a director as an annual retainer for
service in such capacity, as in effect from time to time.

2.9    SAVINGS PLAN means the Biogen Savings Plan, as amended from time to time.
Any term defined in the Savings Plan will have the same meaning when used in
this plan unless otherwise defined herein.

2.10   PLAN YEAR means the period commencing October 1, 1994 and ending December
31, 1994, and the 12-month periods commencing on January 1, 1995 and on each
subsequent January 1 while the plan remains in effect.

                                   ARTICLE 3
                                 PARTICIPATION

3.1    ELIGIBILITY AND PARTICIPATION. Each director will be eligible to be a
participant in this plan as long as he is a director. However, a director who is
also an employee of Biogen (or a subsidiary) will not be eligible to participate
in this plan unless he receives fees and/or retainer separate and apart from his
compensation as an employee, and in such event he will be eligible to
participate in this plan only with respect to such fees and retainer. A director
will become a participant hereunder when he makes a savings deposit to this
plan. Participation in this plan is voluntary and no director will be required
to participate.

3.2    END OF PARTICIPATION. A participant's participation in this plan will end
upon the termination of his service as a director of Biogen because of death,
retirement, resignation, failure of reelection, or any other reason.

       Upon the termination of a participant's participation in this plan in
accordance with this section, the participant may make no further savings
deposits hereunder. However, the participant will be entitled to receive any
amounts in his accounts in accordance with this plan.

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                                    ARTICLE 4
                        SAVINGS DEPOSITS BY PARTICIPANTS

4.1      SAVINGS DEPOSITS AND ELECTIONS.

       (a)    SAVINGS DEPOSITS. Each director may make savings deposits to the
plan from his fees and retainer in any whole percentage of such fees and/or such
retainer, from a minimum of 1% to a maximum of 100%, by agreeing to reduce his
fees and/or retainer by such amount in accordance with this plan.

       All amounts by which a participant reduces his fees and/or retainer
hereunder are referred to herein as the participant's SAVINGS DEPOSITS.

       (b)    SIGN-UP PROCEDURE FOR SAVINGS DEPOSITS. A director who wishes to
reduce his fees and/or retainer with respect to a particular plan year in order
to make savings deposits must complete an enrollment form specifying the amount
of his savings deposits (with separate percentages for his fees and retainer if
desired), agreeing to reduce his fees and/or retainer by the amount(s) desired,
and providing such other information as the committee may require.

       A director's initial enrollment form will also specify the time for
payment (or the commencement of installment payments) under Section 6.3 and the
form of payment (lump sum or installments in accordance with Section 6.4(a)
below) of his accounts hereunder. The time specified for payment may be anytime
the participant indicates, but not later than the latest of the participant's
termination of service as a director, the participant's termination of
employment (if the participant is an employee of Biogen or a subsidiary or
affiliate in addition to being a director), or the participant's 55th birthday.
In addition, a participant's initial enrollment form may (but is not required
to) specify one or more in-service distributions to the participant in
accordance with Section 6.1A if desired by the participant.

       A participant's enrollment form electing savings deposits for any plan
year must be filed with the committee at least two weeks before the start of
such plan year. A participant may change the amount of his savings deposits (but
not the time for payment or the form of payment of his account except as
provided in subsections (c) and (d) below) with respect to any subsequent plan
year by filing a new enrollment form at least two weeks before the start of such
subsequent plan year, and the change will become effective as of the first day
of such subsequent plan year. Once a participant has elected to defer fees
and/or retainer, his enrollment form will remain in effect for future plan years
unless the participant changes or terminates his prior elections by filing a new
enrollment form in accordance with the preceding sentence.

       After a plan year has begun, a participant may not change the amount of
savings deposits (if any) he had elected for such plan year. However, if a
participant has an unforeseeable financial hardship (as defined in Section 6.1)
during a year, the participant may cancel his savings deposits election for the
balance of that year.

       (c)    SPECIAL ONE-TIME ELECTION. Notwithstanding any other provisions of
this plan, each participant who has an account hereunder as of December 1, 2001
may make a special one-time election to change the time for payment (or the
commencement of installment payments) of his savings deposit account balance to
an earlier date specified by him or to elect one or more in-service
distributions in accordance with Section 6.1A if desired. Such special election
must be made before June 30, 2002.

       If any participant makes the election provided for in the preceding
paragraph, the amount specified by the participant for accelerated payment or
in-service distribution under Section 6.1A shall be reduced by ten percent.

       (d)    Notwithstanding subsection (b) above, at anytime prior to the date
for payment originally elected by the participant, if the participant is still a
director of Biogen at such time, the participant may elect to defer the time
when his account would otherwise be payable (or installment payments would
otherwise begin) to a subsequent date specified by him (not later than the
latest time permitted under subsection (b)) or may elect installments (or a
greater number of installments). If such election becomes effective as provided
below, then the participant's account will be payable at the time specified in
his subsequent election. The participant's election under this subsection (d)
will become effective if any of the following criteria is satisfied: (i) the
participant remains a director of Biogen for at least one year after making such
election, or (ii) the participant's service as a director of Biogen ends due to
failure of reelection or due to disability (which means the participant's
inability to perform the material duties of his position because of a physical
or mental illness or condition).

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       A participant may make only one election under this subsection (d) to
further defer payment.

                                   ARTICLE 5
                             PARTICIPANTS' ACCOUNTS

5.1    PARTICIPANT ACCOUNTS.

       (a)    SAVINGS DEPOSITS ACCOUNTS. Savings deposits by a participant from
his fees or retainer hereunder will be credited to an account in the name of
such participant. Such account will be called his savings deposits account.

       (b)    PARTICIPANT'S ACCOUNT VALUE. A participant's account will be
credited with deemed investment results as if his savings deposits were invested
in one or more designated investment funds and all dividends and distributions
on shares of a particular investment fund were reinvested in shares of such
fund. The investment funds available for this purpose will be those from time to
time available as investment options under the Savings Plan (other than the
Biogen stock fund).

       Each participant will indicate with his initial enrollment form the
investment fund or funds (and the proportion in each fund when the participant
designates more than one) he wishes to designate for this purpose. Thereafter, a
participant may change his designation either with respect to the deemed
investment of future savings deposits or the deemed transfer of amounts from a
previously designated investment fund to another fund. The committee shall
establish the frequency by which such a change may be made, the method of making
such a change, and the effective date of such a change and shall prescribe such
other rules and procedures as it deems appropriate. Such designation will remain
in effect until subsequently changed by the participant in accordance with this
paragraph.

       Deemed investment results under this subsection will be credited to a
participant's account effective as of the last day in each calendar quarter (or
such shorter time specified by the committee).

       The value of a participant's account at any point in time will be his
savings deposits, increased or decreased by deemed investment results as
provided in this subsection (b) through the end of the most recently completed
calendar quarter (or such shorter time specified by the committee), and reduced
by any distributions from the participant's account.

       (c)    BOOKKEEPING ACCOUNTS. Participants' accounts and subaccounts will
be maintained on Biogen's books for bookkeeping purposes only; such accounts
will not represent any interest in any trust or in any segregated asset.

       In order to facilitate the administration of the plan, the committee may
arrange for a participant's savings deposits account to be divided for
recordkeeping purposes into two or more subaccounts, in accordance with
procedures established by the committee.

5.2    VESTING. A participant will have a fully vested interest in his savings
deposits account at all times.

                                    ARTICLE 6
                          DISTRIBUTIONS TO PARTICIPANT

6.1    DISTRIBUTIONS FOR FINANCIAL HARDSHIP. If a participant has a serious
financial hardship, he may apply to the committee for a distribution from the
plan prior to his retirement, other termination of service as a director or
other designated time for payment. If such application for a hardship
distribution is approved by the committee, the distribution will be made as soon
as practicable after the later of the date specified in the participant's
application or the date of approval by the committee. The amount of the
distribution will be the amount needed to alleviate the participant's financial
hardship, as determined by the committee, up to a maximum of the participant's
account balance. Such a distribution will be made from the participant's account
in a single lump-sum payment. If such a participant's account has two or more
subaccounts, the committee will determine which subaccount(s) will be debited to
reflect the financial hardship distribution.

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       Financial hardship will be limited to the following: bankruptcy or
impending bankruptcy, unexpected and unreimbursed major expenses resulting from
illness to person or accident to person or property, and to other types of
unforeseeable and unreimbursed expenses of a major nature that normally would
not be budgetable. Financial hardship shall not include foreseeable expenses
such as down payments on a home or purchase of an auto or college or other
educational expenses.

6.1A.  IN-SERVICE DISTRIBUTION(S) AT A TIME SPECIFIED BY PARTICIPANT. If, in his
initial enrollment form (or, if applicable, his one-time election under Section
4.1(c) or (d)), a participant designated payment of his account(s) (or a
specified portion thereof) at a specified time(s) and he is still an employee of
Biogen (or a subsidiary or affiliate) at such time(s), the participant will
receive payment of the amount to be distributed in accordance with such
election, payable on or as soon as practicable after the designated date(s). A
participant's election for in-service distributions under this Section 6.1A may
be for a single payment or up to five annual payments, in each case in an amount
or portion specified by the participant in his enrollment or other election
form. Each payment will be the amount specified (or the entire balance remaining
in the participant's account, if less).

       Any amount in a participant's account hereunder not distributed to the
participant under this Section 6.1A will be distributed under Section 6.2 or
6.3, whichever may be applicable, and Section 6.4 (if applicable). If a
participant is receiving multiple payments under this Section 6.1A and retires,
dies or otherwise terminates service (or employment if he is also an employee of
Biogen or a subsidiary or affiliate), payments under this subsection will cease
and subsequent payments will be governed by Section 6.2 or 6.3, as the case may
be.

6.2      DISTRIBUTION UPON DEATH OF A PARTICIPANT.

(a)    IN GENERAL. If a participant dies before his entire account balance has
been distributed, his beneficiary will receive the amount remaining in the
participant's account. Distribution will be made in a single sum payment on a
date determined by the committee, but not later than one year after the
committee receives such evidence of the participant's death and of the right of
any beneficiary to receive payment as it deems necessary.

(b)    BENEFICIARY. A participant may designate one or more beneficiaries to
receive a distribution payable under subsection (a) above and may revoke or
change such a designation at any time. If the participant names two or more
beneficiaries, distribution to them will be in such proportions as the
participant designates or, if the participant does not so designate, in equal
shares. Any designation of beneficiary will be in writing on such form as the
committee may prescribe or deem acceptable, and will be effective upon filing
with the committee.

       Any portion of a distribution payable upon the death of a participant
that is not disposed of by a designation of beneficiary under the preceding
paragraph, for any reason whatsoever, will be paid to the participant's spouse
if living at his death, otherwise equally to the participant's natural and
adopted children (and the issue of a deceased child by right of representation),
otherwise to the participant's estate.

       The committee may direct payment in accordance with a prior designation
of beneficiary (and will be fully protected in so doing) if such direction (i)
is given before a later designation is received, or (ii) is due to the
committee's inability to verify the authenticity of a later designation. Such a
distribution will discharge all liability therefor under the plan.

6.3    OTHER DISTRIBUTIONS. Except in the case of the participant's death (in
which case distribution is made in accordance with Section 6.2), distribution of
a participant's account will be made at the time elected by the participant in
accordance with Section 4.1. In the absence of such an election, distribution of
the participant's account will be made following the latest of the participant's
termination of service as a director, the participant's termination of
employment (if the participant is an employee of Biogen or a subsidiary in
addition to being a director) or the participant's 55th birthday. Distribution
will be made in a single lump sum payment on a date determined by the committee,
but not later than one year after the committee's receipt of satisfactory
evidence of the occurrence of the event causing distribution.

6.4    INSTALLMENT DISTRIBUTIONS IN CERTAIN CASES.

       (a)    PARTICIPANT. Notwithstanding the provisions of Section 6.3, a
participant may, at the time of filing his initial enrollment form under Section
4.1 (or, if applicable) in a subsequent election under Section 4.1(c) or (d),

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designate that the amount payable to him hereunder will be paid in a number
(minimum of two and maximum of ten) of annual installment payments, as specified
by the participant.

       (b)    BENEFICIARY. Notwithstanding Section 6.2, a participant may
designate that, if the participant dies before receiving the entire amount
payable to him hereunder, the beneficiary will receive either:

              (i)    A number of annual installment payments equal to:

                     (A)    the number the participant elected for himself under
                            subsection (a) above (if the participant dies before
                            receiving any installment payments), or

                     (B)    the number of remaining installment payments due to
                            the participant under subsection (a) above (if the
                            participant dies after receiving one or more
                            installment payments); or

              (ii)   a single payment.

       Payment to the beneficiary will be made or begin as provided in Section
6.2(a).

       If the participant fails to designate the form of payment to the
beneficiary, the default form will be installments under (i) above. If
installment payments are payable to the beneficiary, with the consent of the
committee, a participant may subsequently change the form of payment to his
beneficiary (but not the form of payment to himself under Section 6.3), to a
single payment by filing a written instrument so specifying with the committee.

       (c)    INSTALLMENT PAYMENTS. Where installment payments are due, the
first annual installment payment will be paid out on the date specified in
Section 6.2 or 6.3 (whichever is applicable) and subsequent annual installments
will be paid approximately on succeeding anniversaries of the first payment
date. The amount of each annual installment payment will be determined by
multiplying the amount to be paid by a fraction whose numerator is one and whose
denominator is the number of remaining annual installment payments.

       (d)    DEATH OF BENEFICIARY. If a participant's designated beneficiary is
receiving installment payments and dies before receiving payment of all the
annual installments, the designated beneficiary's estate will receive a lump-sum
payment of the amount remaining to the distributed to such deceased beneficiary.
Such payment will be made as soon as practicable after the committee's receipt
of satisfactory evidence of the death of the designated beneficiary.

                                    ARTICLE 7
                                  MISCELLANEOUS

7.1    AMENDMENT OR TERMINATION OF PLAN. Biogen, by action of the Board (or such
committee thereof or officer or officers of Biogen to whom the Board has
delegated this authority), at any time and from time to time, may amend or
modify any or all of the provisions of this plan or may terminate this plan
without the consent of any participant (or beneficiary or other person claiming
through a participant). No termination or amendment of the plan may reduce the
amount credited to the account of any participant under the plan (including a
participant whose service as a director terminated before such plan termination
or amendment). However, Biogen may change the deemed investment options under
Section 5.1(c), and Biogen may upon termination of this plan pay participants'
account balances to the participants regardless of the times elected for payment
(or the start of installment payments) elected by the participants and may pay
such amounts in single sum payments regardless of whether participants have
elected installment distributions under Section 6.4.

7.2    BENEFITS NOT CURRENTLY FUNDED.

       (a)    Nothing in this plan will be construed to create a trust or to
obligate Biogen to segregate a fund, purchase an insurance contract or other
investment, or in any other way currently to fund the future payment of any
benefits hereunder, nor will anything herein be construed to give any
participant or any other person rights to any

                                       5
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specific assets of Biogen or any other entity. However, in order to make
provision for its obligations hereunder, Biogen may in its discretion purchase
an insurance contract or other investment; any such contract or investment will
be a general asset belonging to Biogen, and no participant or beneficiary will
have any rights to any such asset. The rights of a participant or beneficiary
hereunder will be solely those of a general, unsecured creditor of Biogen.

       (b)    Notwithstanding subsection (a) above, Biogen in its sole
discretion may establish a grantor trust of which it is treated as the owner
under Code Section 671 to provide for the payment of benefits hereunder, subject
to such terms and conditions as Biogen may deem necessary or advisable to ensure
that benefits are not includable, by reason of the trust, in the taxable income
of trust beneficiaries before actual distribution and that the existence of the
trust does not cause the plan or any other arrangement to be considered funded
for purposes of Title I of ERISA.

7.3    NO ASSIGNMENT. No participant or beneficiary will have any power or right
to transfer, assign, anticipate or otherwise encumber any benefit or amount
payable under this plan, nor shall any such benefit or amount payable be subject
to seizure or attachment by any creditor of a participant or a beneficiary, or
to any other legal, equitable or other process, or be liable for, or subject to,
the debts, liabilities or other obligations of a participant or beneficiary
except as otherwise required by law.

7.4    RESPONSIBILITIES AND AUTHORITY OF COMMITTEE. The committee will control
and manage the operation and administration of the plan except to the extent
that such responsibilities are specifically assigned hereunder to Biogen or the
Board.

       The committee will have all powers and authority necessary or appropriate
to carry out its responsibilities for the operation and administration of the
plan. It will have discretionary authority to interpret and apply all plan
provisions and to correct any defect, supply any omission or reconcile any
inconsistency or ambiguity in such manner as it deems advisable. It will make
all final determinations concerning eligibility, benefits and rights hereunder,
and all other matters concerning plan administration and interpretation. All
determinations and actions of the committee will be conclusive and binding upon
all persons, except as otherwise provided herein or by law, and except that the
committee may revoke or modify a determination or action previously made in
error. It is intended that any action or inaction by the committee will be given
the maximum possible deference by any reviewing body (whether a court or other
reviewing body), and will be reversed by such reviewing court or other body only
if found to be arbitrary and capricious.

       Biogen will be the "plan administrator" and the "named fiduciary" for
purposes of the Employee Retirement Income Security Act of 1974, as amended.

7.5    LIMITATION ON RIGHTS CREATED BY PLAN. Nothing appearing in the plan will
be construed (a) to give any person any benefit, right or interest except as
expressly provided herein, or (b) to create a contract of employment or to give
any director the right to continue in such capacity or to affect or modify the
terms of his service as a director in any way.

7.6    TAX WITHHOLDING. Any payment hereunder to a participant or beneficiary
will be subject to withholding of income and other taxes to the extent required
by law.

7.7    TEXT CONTROLS. Headings and titles are for convenience only, and the text
will control in all matters.

7.8    APPLICABLE STATE LAW. To the extent that state law applies, the
provisions of the plan will be construed, enforced and administered according to
the laws of the Commonwealth of Massachusetts.

                                       6<PAGE>
                                                                   EXHIBIT 10.42

[BIOGEN LOGO]                                    VICE PRESIDENT, HUMAN RESOURCES
--------------------------------------------------------------------------------
FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA 02142 * 617-679-2000 * FAX 617-679-3595

                                 June 21, 2000

Mr. Peter N. Kellogg
3617 Dartmouth Avenue
Dallas, Texas 75205

Dear Peter:

This letter supercedes my letter dated June 19 and represents Jim Mullen's offer
to you on behalf of Biogen. You are offered the position of Vice President and
Chief Financial Officer of Biogen at an annual salary of $325,000. You will
report directly to Jim Mullen and you will become a member of the Biogen
Operating Team. Consistent with Biogen's compensation policy, you will be
eligible for a pro-rated merit salary review at year-end 2000 and annually
thereafter. You will also be eligible to participate in Biogen's annual
incentive compensation plan with a 50% target bonus and assuming an August 1,
2000 start date, Biogen will guarantee a pro-rated target bonus of $68,250 for
year 2000. Your principal place of employment will be at Biogen's headquarters
in the Cambridge, Massachusetts area.

Upon employment you will receive $200,000 as a one-time special cash bonus,
which will be treated as an interest-free forgivable loan. The bonus will be
forgiven over a thirty-six month, straight-line schedule. In the event you
voluntarily terminate your employment, or Biogen terminates your employment for
poor performance or cause, prior to the thirty-six months from the date of the
loan, the unforgiven portion of the loan would be payable to Biogen within six
months of your termination date. If your employment is involuntarily terminated
for non-cause within the first three years, or there is a change of control that
results in your termination, the full balance of this loan will be forgiven.

As of the date you commence employment, you will be granted an option to
purchase 200,000 shares of the common stock of Biogen, Inc. The exercise price
per share will be the average of the high and low sale prices as reported in the
National Association of Securities Dealers Automated Quotation System ("NASDAQ")
on the date you commence employment. The option will have a ten-year term and
vest over a five-year period at the rate of 20% per year starting on the
anniversary of the date you commence employment. Based on your performance you
will be eligible for a merit stock option grant at year-end 2000 pursuant to
Biogen's merit stock option policy. This grant will be comparable with awards
granted to the three most senior executive officers reporting to Jim Mullen.

You will be able to choose from a menu of benefit options through our flexible
benefits program, BioChoice. These include health care, life, dependent life,
and disability insurance as well as two flexible spending accounts, Med-Flex and
D-Flex, for eligible medical or dependent-care expenses. At the beginning of the
calendar quarter following your date of hire you will be eligible to participate
in Biogen's pension and 401(k) savings plans. Biogen also offers a variety of
additional benefits including childcare and elder care referral service,
educational matching gifts, credit union, and group

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[BIOGEN LOGO]                                    VICE PRESIDENT, HUMAN RESOURCES
--------------------------------------------------------------------------------
Mr. Peter N. Kellogg
June 21, 2000
Page 2

homeowners and automobile insurance. You will receive more detailed information
regarding your benefits on your first day of employment.

Biogen will provide relocation benefits to facilitate your move from Dallas,
Texas. A relocation counselor will contact you to discuss the relocation
program, and will send you a package detailing the relocation policy to you.
These benefits will include the reimbursement of many of the costs associated
with both the sale of your current house and the purchase of a new house in the
Boston area; temporary living; return trips home; home finding; and movement of
your household goods. Please read the policy carefully as it will outline the
parameters of these benefits and detail the reimbursement process.

In addition, Biogen will also provide the following supplemental relocation
benefits:

-    BRIDGE LOAN: We will provide a bridge loan on the equity of your home in
     Dallas, which will be in place for up to six months, if necessary. We will
     consider an extension beyond this period if unusual market conditions do
     not allow the sale of your home.

-    MORTGAGE LOAN: Biogen will also provide you a fully subordinated
     interest-free mortgage loan of $1,000,000 (secured by real property of your
     choice and with prompt substitution of security permitted on your
     reasonable request, providing that the security shall consist of your
     principal residence in the Boston area once you acquire one). The mortgage
     loan will be repayable to Biogen the sooner of five years from your date of
     employment or eighteen months following the point in time the pre-tax
     profit of your vested stock options exceeds $5,000,000. In the event that
     the pre-tax profit of your vested options does not exceed $5,000,000 five
     years from your date of employment, the payment date of the mortgage loan
     will be extended for up to two years following your fifth anniversary date.

-    MORTGAGE REIMBURSEMENT: If necessary, Biogen will reimburse you for the
     mortgage and other reasonable costs related to your property in Dallas for
     up to six months. This reimbursement will commence after you have purchased
     a home in the Boston area and will end on the earlier of (i) six months, or
     (ii) when you have closed on the sale of your Dallas property.

If you voluntarily terminate your employment or if your employment is terminated
by Biogen for cause, you will be required to repay Biogen the entire amount of
the loan the sooner of six months following the termination of your employment
or the closing on the sale of the property by which the loan is then secured. If
your employment is involuntarily terminated for non-cause within the first five
years, or there is a change of control that results in your termination, your
loan will be forgiven. The Company has the right to renegotiate this change of
control clause if there is a new change of control provision, but will guarantee
that it will be no less favorable than the agreement set forth in this
employment letter.

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[BIOGEN LOGO]                                    VICE PRESIDENT, HUMAN RESOURCES
--------------------------------------------------------------------------------
Mr. Peter N. Kellogg
June 21, 2000
Page 3

As an officer of the Company, you will be required to participate in our program
for executive stock ownership. We believe it is very important that our key
leaders have personal stock ownership. I will outline the program to you.

Additionally, in your new role you will be provided the following:

-    VACATION: You are entitled, during your employment with Biogen, to four (4)
     weeks vacation, accrued on a monthly pro-rated basis.

-    SUPPLEMENTAL SAVINGS PLAN: You are entitled, during your employment with
     Biogen, to participate in the Voluntary Executive Supplemental Savings
     Plan. This plan allows you to defer from your current taxation up to 50% of
     your base salary and 100% of your bonus, if there is one. I can outline the
     details of the program if you are interested in participating.

-    LIFE INSURANCE: You will be provided, during your employment with Biogen,
     Biogen's Executive Term Life Insurance coverage for a total of $1,000,000.
     This coverage is based on your successfully meeting the medical standards
     as stated in the Executive Term insurance policy.

-    TAX REVIEW/PREPARATION: You are entitled, during your employment with
     Biogen, to the preparation and/or review, including review of estimated
     taxes of your annual Federal and State tax returns, which is currently
     administered through Price WaterhouseCoopers. The cost of this service is
     covered by Biogen. In the event you choose to continue the services
     provided by your current tax advisor, Biogen will reimburse you the cost of
     these services up to but not exceeding the amount incurred by Biogen
     through Price WaterhouseCoopers.

-    INVOLUNTARY TERMINATION: If your employment with Biogen is terminated by
     Biogen without cause, Biogen will protect you by paying you a supplementary
     amount (the "Supplementary Amount") equal to your then present base salary
     for a period (the "Extra Period") ending on the earlier of (i) the date
     twelve months from your termination and (ii) the date you start another
     job. During such period, Biogen will also pay to continue your health
     benefits (i.e., health and dental plan coverage), provided such benefits
     are accorded employees generally and Biogen can obtain the relevant
     coverage. If you need continued coverage to prevent a gap in health
     coverage between your Biogen coverage and that at your new job, Biogen will
     extend such coverage for up to 30 days (to the extent that the Extra Period
     is less than twelve months) after you start your new job. The Supplementary
     Amount will be paid on the same schedule as your salary would have been
     paid. You will not be an employee of Biogen during the time of such
     payments and will not accrue any benefits or other rights (such as, but not
     limited to, pension plan vesting or accrual, stock option

<PAGE>
[BIOGEN LOGO]                                    VICE PRESIDENT, HUMAN RESOURCES
--------------------------------------------------------------------------------
Mr. Peter N. Kellogg
June 21, 2000
Page 4

     vesting, vacation pay, etc.) during such period except health benefits as
     described above. You agree to notify us when you accept a new job.

Commencement of employment with Biogen is contingent on the satisfactory
completion of a pre-employment drug screening test at least five business days
prior to your start date. We require all new employees to sign an Intellectual
Property/Confidentiality Agreement on the first day of employment. You will also
be required to complete a medical history review with our occupational health
department, which is scheduled after your first day of employment.

It is Biogen's policy to comply with federal, state and local guidelines
applicable to its facilities and to take all reasonable steps to ensure the
health and safety of Biogen employees. Consistent with this policy, your normal
duties may require you from time to time to attend meetings or perform functions
in any or all of Biogen's facilities.

The Federal Government requires you to provide proper identification verifying
your eligibility to work in the United States. Please bring the appropriate
identification with you on your first day of employment.

On behalf of Jim Mullen, we very much look forward to your positive response and
to your joining us as early as practical. We are confident that you will make a
significant contribution to Biogen's future success.

Please confirm your acceptance by signing this offer letter and noting your
preferred start date. I also invite you to complete the enclosed invitation to
self-identify. Please complete the employment application and the drug screen
authorization forms and then return both signed documents to me in the enclosed
self addressed, stamped envelope. The other original offer letter is for your
records.

                                        Sincerely,

                                        /s/ Frank A. Burke, Jr.
                                        ------------------------------------
                                        Frank A. Burke, Jr.

FAB:bk
Attachments

cc: Mr. James C. Mullen

<PAGE>
[BIOGEN LOGO]                                    VICE PRESIDENT, HUMAN RESOURCES
--------------------------------------------------------------------------------
Mr. Peter N. Kellogg
June 21, 2000
Page 5

I am pleased to accept the offer of employment described above:

ACCEPTED:

/s/ Peter N. Kellogg                                               8/7/00
--------------------------------------------------------------------------------
Peter N. Kellogg                                            Preferred Start Date

For timely processing of your medical and dental benefit enrollment forms please
fill in the appropriate information:

Birth Date: 3/20/56                       Social Security Number: ###-##-####
            -------                                               -----------

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