Exhibit 10.9

                              EMPLOYMENT AGREEMENT

      THIS AGREEMENT, dated as of 3rd October, 1994 (the "Effective Date"), is
made by and among VERTEX PHARMACEUTICALS INCORPORATED, a Massachusetts
corporation ("Vertex"), its wholly-owned subsidiary, VERTEX PHARMACEUTICALS
(EUROPE) LIMITED, a U.K. limited liability company (the "Company"), and IAIN
P.M. BUCHANAN (the "Executive").

Recitals:

      The Company wishes to engage the services of the Executive as a key
employee of the Company and the Executive wishes to perform such services. The
Board of Directors of Vertex has determined that it is in the best interests of
the Company and Vertex to assure that the Company will have the continued
dedication of the Executive. The Board believes that it is important to
encourage the Executive's full attention and dedication to the Company currently
and in the event of any threatened or pending Change of Control of Vertex (as
hereinafter defined), and to provide the Executive with compensation
arrangements which provide the Executive with individual financial security in
the event of certain terminations of employment, including termination upon a
Change of Control, and which are competitive with those of other corporations.
In order to accomplish these objectives Vertex, the Company and the Executive
agree as follows:

1. Definitions. For purposes of this Agreement:

      1.1 "Cause" shall mean (i) the willful and continued failure by the
Executive to substantially perform his duties with the Company (other than any
such failure resulting from the Executive's incapacity due to physical or mental
illness or any such failure after the issuance of a notice of termination in
accordance with Section 11.8 by the Executive for Good Reason, as hereinafter
defined) after a written demand for substantial performance is delivered to the
Executive by the Board of Directors of Vertex, which demand specifically
identifies the manner in which the Board believes that the Executive has not
substantially performed his duties, or (ii) the willful engaging by the
Executive in conduct which is demonstrably and materially injurious to the
Company, monetarily or otherwise, or (iii) any conduct on the part of the
Executive (whether or not in the course of his duties) which, in the reasonable
opinion of the Board, has or is likely to bring himself, the Company or Vertex
into serious disrepute, or which causes the Board to lose all trust and
confidence in him, or (iv) the voluntary resignation by the Executive of his
office as a director of the Company or his disqualification from being a
director, or (v) the Executive becoming bankrupt or making any arrangement or
composition with his creditors generally.

      1.2 "Disability" shall have the same meaning as in the Company's long-term
disability insurance coverage in effect on the applicable date, or, if the
Company carries no such insurance, the Executive's inability to perform the
Executive's duties hereunder for a period of 90 consecutive days by reason of
physical or mental illness or incapacity.


                                      -1-


      1.3 "Good Reason" shall mean:

(i) at any time during the term hereof, without the Executive's express written
consent, the occurrence of any of the following:

      (a)   a substantial adverse alteration in the nature or status of the
            Executive's position or responsibilities or the condition of his
            employment;

      (b)   a reduction by the Company in the Executive's annual base salary;

      (c)   the failure by the Company to pay to the Executive any portion of
            his current compensation or compensation under any deferred
            compensation program of the Company within seven (7) days after the
            date such compensation is due;

      (d)   any purported termination by the Company of the Executive's
            employment which is not effected pursuant to a notice of termination
            satisfying the requirements of the applicable provisions of this
            Agreement, which purported termination shall not be effective for
            purposes of this Agreement;

      (e)   any act or omission to act on the part of the Company which causes
            the Executive to lose all trust and confidence in it as his
            employer; or

(ii) during the nine (9) month period following a Change in Control of Vertex
(as hereinafter defined):

      (a)   the assignment to the Executive of any duties inconsistent in any
            respect with the Executive's position (including status, offices,
            titles, and reporting requirements), authority, duties or
            responsibilities as contemplated by Section 4 of this Agreement or
            any other action by the Company which results in a diminishment in
            such position, authority, duties or responsibilities; or

      (b)   the failure by the Company to continue in effect after such Change
            in Control any material compensation or benefit plan in which the
            Executive participates immediately prior to such Change in Control,
            unless an equitable arrangement has been made with respect to such
            plan, on a basis not materially less favorable, both in terms of the
            amount of benefits provided and the level of his participation
            relative to other participants, or the failure of the Company to
            continue the Executive's participation therein (or in such
            substitute or alternative plan); or

(iii) the failure of the Company or Vertex to obtain a satisfactory agreement
from any successor to assume and agree to perform this Agreement, as
contemplated in Section 11.5.1 hereof

      1.4 "Change in Control" shall mean a change in control of Vertex of a
nature that would be required to be reported in response to Item 6(e) of
Schedule 14A of Regulation 14A promulgated under the U.S. Securities Exchange
Act of 1934, as amended (the "Exchange Act"), whether or not Vertex is in fact
required to comply therewith; provided, that, without limitation, a Change in
Control shall be deemed to have occurred if:

      (A) any individual, firm, corporation or other entity ("Person") becomes
an Acquiring Person (as hereinafter defined), except to the extent that such
Person is deemed to have acquired Beneficial Ownership (as hereinafter defined)
of 20% or more of the voting shares of Vertex because all or some of such voting
shares were acquired pursuant to an Approved Transaction (as hereinafter
defined);


                                      -2-


      (B) during any period of twenty-four (24) consecutive months (not
including any period prior to the Effective Date), individuals who at the
beginning of such period constitute the Board of Directors of Vertex and any new
directors (other than a director designated by a person who has entered into an
agreement with Vertex to effect a transaction described in paragraphs (A), (C)
or (D) of this section) whose election by the Board of Directors of Vertex or
nomination for election by the stockholders of Vertex was approved by a vote of
at least two-thirds (2/3) of the directors then still in office who either were
directors at the beginning of such period or whose election or nomination for
election was previously so approved, cease for any reason to constitute a
majority thereof; or

      (C) the stockholders of Vertex approve a merger or consolidation of Vertex
with any other corporation, other than (a) a merger or consolidation which would
result in the voting shares of Vertex outstanding immediately prior thereto
continuing to represent (either by remaining outstanding or by being converted
into voting shares of the surviving entity) at least 50% of the combined voting
shares of Vertex or such surviving entity outstanding immediately after such
merger or consolidation or (b) a merger or consolidation effected to implement a
recapitalization of Vertex (or similar transaction) in which no Person becomes
an Acquiring Person; or

      (D) the stockholders of Vertex approve a plan of complete liquidation of
Vertex or an agreement for the sale or disposition by Vertex of all or
substantially all of Vertex's assets.

      For purposes hereof:

            1.4.1 "Acquiring Person" shall mean any Person who or which,
together with all Affiliates and Associates of such Person, shall be the
Beneficial Owner of 20% or more of the shares of the voting shares of Vertex
then outstanding, but shall not include Vertex, any subsidiary of Vertex, any
employee benefit plan of Vertex or any subsidiary of Vertex, any entity holding
Common Shares for or pursuant to the terms of any such plan, or any Person who,
alone or together, with all Affiliates and Associates of such Person, is, as of
the Effective Date of this Agreement, the Beneficial Owner of 20% or more of the
voting shares of Vertex. Notwithstanding the foregoing, no Person shall become
an "Acquiring Person" as the result of an acquisition of Common Shares by Vertex
which, by reducing the number of shares outstanding, increases the proportionate
number of shares beneficially owned by such Person to 20% or more of the voting
shares of Vertex outstanding; provided, however, that if a Person shall become
the Beneficial Owner of 20% or more of the Common Shares of Vertex then
outstanding by reason of share purchases by Vertex and shall, after such share
purchases by Vertex, become the Beneficial Owner of any additional voting shares
of Vertex, then such Person shall be deemed to be an "Acquiring Person".

            1.4.2 "Affiliates" and "Associates" shall have the respective
meanings ascribed to such terms in Rule 12b-2 of the General Rules and
Regulations under the Exchange Act.

            1.4.3 "Beneficial Owner" and "Beneficial Ownership" shall have the
respective meanings ascribed to such terms in Rule 13d-3 of the General Rules
and Regulations under the Exchange Act.

            1.4.4 "Approved Transaction" shall mean any purchase of Beneficial
Ownership of voting shares of Vertex directly from Vertex in a transaction
expressly and affirmatively approved by a vote of at least two thirds (2/3) of
those members of the Board of Directors of Vertex, voting separately and as a
subclass of directors on such transaction, who are not and do not, pursuant to
such transaction, become Acquiring Persons or Affiliates or Associates of an
Acquiring Person or representatives of an Acquiring Person or of any such
Affiliate or Associate.


                                      -3-


2. Employment.

      The Company hereby agrees to employ the Executive, and the Executive
hereby accepts employment by the Company, upon the terms and conditions set
forth herein and in the schedules to this Agreement.

3. Effective Date and Term.

      This Agreement shall take effect as of the Effective Date, and shall
continue in full force and effect until terminated in accordance with the
provisions of this Agreement. The provisions of Sections 6 and 7 of this
Agreement shall survive any termination or expiration of this Agreement, in
accordance with their terms.

4. Title and Duties.

      The Executive shall promote the business and affairs of the Company as
Managing Director of the Company, with responsibility for performing such duties
consistent with such position as the Board of Directors of the Company may from
time to time designate. In addition, the Executive shall serve as Vice
President-Europe of Vertex, with responsibility for performing such duties
consistent with such position as the Chief Executive Officer of Vertex may from
time to time designate. Except as otherwise provided in this Agreement and
except for vacations and absences due to temporary illness in accordance with
Company policies in effect from time to time, the Executive shall devote his
full working time and efforts to the business and affairs of the Company, and
shall comply, to the best of his abilities, with all reasonable directions given
him by the Board of Directors of the Company or the Chief Executive Officer of
Vertex.

5. Compensation and Benefits.

      In consideration for the services rendered by the Executive under this
Agreement, the Executive shall receive a base salary as determined annually by
the Compensation Committee of the Board of Directors of Vertex or by the full
Board of Directors of Vertex, and such bonuses, stock option grants and other
compensation as may be determined from time to time by the Compensation
Committee or the Board of Directors of Vertex. In addition, the Executive shall
be entitled to such life insurance, health insurance and other employee benefits
as may be offered or generally made available by the Company to its executive
employees from time to time, and which are at least substantially equivalent to
those offered or generally made available to Vertex's United States executive
employees and which are described in Schedule 1 to this Agreement.

6. Termination; Severance.

      6.1 Death. In the event of termination by reason of the Executive's death,
the Executive's estate shall not be entitled to any compensation or benefits
hereunder accruing after the date of death, except as otherwise provided under
the Company's benefit plans as then in effect.

      6.2 Disability. In the event of the Executive's Disability, the
Executive's employment hereunder shall terminate, at the election of the
Company, upon not less than thirty (30) days prior written notice duly given to
the Executive, unless the Executive shall have returned to the full-time
performance of his duties hereunder prior to the effective date of such
termination. In the event of any dispute concerning the existence of a
Disability, such question shall be determined by a licensed physician selected
by the Company and reasonably acceptable to the Executive, whose determination
shall be final and binding upon the parties. The Executive shall submit to such
examinations and furnish such information as such physician may reasonably


                                      -4-


request. In the event of termination by reason of Disability, the Executive
shall not be entitled to any compensation or benefits hereunder accruing after
the effective date of termination, except as otherwise provided under the
Company's benefit plans as then in effect.

      6.3 Termination for Cause. The Company may terminate the Executive's
employment hereunder at any time for Cause by written notice duly given to the
Executive. No such notice of termination for Cause shall be effective unless
accompanied by a copy of a resolution duly adopted by the affirmative vote of
not less than two-thirds (2/3) of the entire membership of the Board of
Directors of Vertex (after reasonable notice to the Executive and an opportunity
for the Executive to be heard before the Board), finding that in the good faith
opinion of the Board the Executive was guilty of the conduct set forth in
Section 1.1 and specifying the particulars in detail. In the event of
termination for Cause, the Executive shall not be entitled to any compensation
or benefits hereunder accruing after the effective date of termination, except
as otherwise provided under the Company's benefit plans as then in effect.

      6.4 Termination Without Cause. The Company may terminate the Executive's
employment hereunder without Cause by written notice duly given to the Executive
not less than six (6) months prior to the effective date of such termination.
Except as otherwise provided in Section 7 with respect to a termination after a
Change in Control, or as otherwise provided under the Company's benefit plans as
then in effect, the Executive shall not be entitled to any compensation or
benefits hereunder accruing after the effective date of termination. The Company
reserves the right to pay salary (less statutory deductions) in lieu of notice.

      6.5 Termination by the Executive. The Employee may terminate his
employment hereunder effective as of any date on or after 3 October 1995 upon
not less than six (6) months prior written notice to the Company.
Notwithstanding anything in this Agreement to the contrary, a termination of
employment by the Executive for Good Reason pursuant to written notice duly
given in accordance with Section 11.8 shall be deemed a termination of the
Executive by the Company without Cause, and not a voluntary termination by the
Executive. Except as otherwise provided in Section 7 with respect to a
termination after a Change in Control, in the event of termination for Good
Reason, the Executive shall be entitled to severance pay in an amount equal to
six (6) months' base salary (as in effect on the date the notice of termination
is given, payable in a lump sum within ten (10) business days after the
effective date of termination.

      6.6 Reduction for Certain Payments. Any payments to be made under this
Agreement following the termination of the Executive's employment pursuant to
any provision of this Agreement shall be reduced by an amount equal to any
amount(s) which the Company may then be obliged to pay to the Executive as a
result of that termination pursuant to the Employment Protection (Consolidation)
Act 1978 by way of a statutory redundancy payment, a Basic Award and/or the
maximum Compensatory Award.

7. Change in Control

      7.1 Termination Following Change in Control. Notwithstanding anything in
this Agreement to the contrary, if the Executive's employment is terminated
after a Change in Control shall have occurred, either (i) by the Company without
Cause, or (ii) by the Executive for Good Reason, the Executive shall, in
accordance with the resolution of the Company of even date herewith approving
the terms of this contract and, in particular, the payment envisaged by this
clause, be entitled to the following benefits:

            7.1.1 The Company shall pay the Executive his full base salary up to
and including the date of termination at the rate in effect on the date the
notice of termination is


                                      -5-


given, plus all other amounts to which he is entitled under any compensation or
benefit plan of the Company as of the date of termination.

            7.1.2 In compensation for the Executive's likely loss of earnings by
reason of the early termination of his employment and any consequent disruption
to his career prospects, the Company shall pay as severance pay to the Executive
a lump sum payment equal to three (3) times the sum of (i) the Executive's
annual rate of base salary in effect immediately prior to the Change in Control,
and (ii) the average of the last two annual bonuses (annualized in the case of
any bonus paid with respect to a partial year) paid to the Executive preceding
the Change in Control, payable within ten (10) business days after the date of
termination. The amount payable pursuant to this Section 7.1.2 shall be reduced
by the amount of any payments made in lieu of notice or severance pay pursuant
to Sections 6.4 or 6.5.

            7.1.3 All rights, options and awards held by the Executive under any
stock option, stock purchase or other equity incentive plan or agreement of the
Company or Vertex shall be fully vested and not subject to forfeiture or
repurchase on account of the termination of employment, notwithstanding any
provision to the contrary contained in such plan or agreement.

            7.1.4 For three (3) years after the date of termination, the Company
shall provide the Executive with life, disability, accident and health insurance
benefits substantially similar to those which the Executive was receiving
immediately prior to the Change in Control. Benefits otherwise receivable by the
Executive pursuant to this Section 7.1.4 shall be reduced to the extent
comparable benefits are actually received by the Executive from a subsequent
employer during such period, and any such benefits actually received by the
Executive shall be reported to the Company.

            7.1.5 The Company shall also pay to the Executive, within ten (10)
business days after any such fees or expenses are incurred, all legal fees and
expenses incurred by the Executive as a result of or in connection with such
termination, including all such fees and expenses, if any, incurred in seeking
to obtain or enforce any right or benefit provided by this Agreement or in
connection with any tax audit or proceeding to the extent attributable to the
application of Section 4999 of the U.S. Internal Revenue Code of 1986, as
amended (the "Code"), to any payment or benefit provided hereunder.

      7.2 No Mitigation. The Executive shall not be required to mitigate the
amount of the severance payment or any other benefit provided under this Section
7 by seeking other employment or otherwise, nor shall the amount of any payment
or benefit provided for in this Section 7 be reduced by any compensation earned
by the Executive as the result of employment by another employer, by retirement
benefits, by offset against any amount claimed to be owed by the Executive to
the Company, or otherwise, except to the extent expressly so provided.

8. AGREEMENT NOT TO COMPETE.

      The Executive acknowledges the unique nature of the business of Vertex and
the need of Vertex to maintain its competitive advantage in the industry through
the protection of its trade secrets and proprietary information. Accordingly,
the Executive agrees that for a period of one (1) year after the termination of
his employment, the Executive shall not, directly or indirectly, within the
United States of America or its territories or possessions or within any other
country in which Vertex conducts or plans to conduct its business or distributes
any of its products or renders any services (determined in each case as of the
employment termination date and in relation only to those aspects of its
business and those products and services with which the Executive shall have had
a material involvement), engage in business with, own an interest in, be
employed by, or consult or advise for, any person or entity (except as a holder
of not more than a two percent (2%) equity interest in a publicly-traded entity)
which is in competition with the


                                      -6-


business of Vertex, provided that the foregoing shall not preclude the
Executive's employment by any multi-divisional employer having a division which
engages in activities in competition with the business of Vertex so long as the
Executive shall not be involved in the operations or management of such
competitive division. For purposes hereof, an entity shall be deemed to be in
competition with the business of Vertex if it is engaged in the discovery of
novel pharmaceuticals, using structure-based rational drug design as its primary
research methodology.

      The Executive further agrees that for a period of one (1) year after
termination of this Executive's employment hereunder he will not, directly or
indirectly:

(i) endeavor to entice away from the Company or Vertex any senior employee or
consultant employed or engaged in a sales or technical capacity with whom he
shall have worked at any time during the period of 12 months preceding the
termination of his employment; or

(ii) solicit the custom of any client, supplier, customer or business partner of
the Company or Vertex with whom or which the Executive shall have dealt
personally to any material extent during the period of 12 months preceding the
termination of his employment or in relation to which he shall possess any
confidential information or seek by any means to induce such client, supplier,
customer or business partner to terminate his, her or its relationship with the
Company or Vertex.

9. FREEDOM TO CONTRACT.

      The Executive represents that he is free to enter into this Agreement,
that he has not made and will not make any agreements in conflict with this
Agreement. The Executive will not, and the Company will not require the
Executive to, disclose to the Company, or use for the Company's benefit, any
trade secrets or confidential information now or hereafter in the Executive's
possession which is the property of any other party. In particular, the
Executive agrees to be bound by the terms of the Employee Non-Disclosure and
Inventions Agreement attached as Schedule 2 hereto.

10. REMEDIES.

      The parties agree and acknowledge that the rights and obligations set
forth under this Agreement are of a unique and special nature and that the
Company and Vertex are, therefore, without an adequate legal remedy in the event
of Executive's violation of the covenants set forth in this Agreement. The
parties agree, therefore, that the covenants made by the Executive under this
Agreement shall be specifically enforceable in equity, in addition to all other
rights and remedies, at law or in equity or otherwise (including termination of
employment) that may be available to the Company or Vertex.

11. PROVISIONS OF GENERAL APPLICATION.

      11.1 Governing Law. This Agreement and the rights and obligations of the
parties hereunder shall be construed, interpreted and determined in accordance
with the laws of England and Wales.

      11.2 Other Agreements. This Agreement represents the entire understanding
and agreement between the parties as to the subject matter hereof and supersedes
all prior or concurrent oral or written agreements relating thereto, including
without limitation the Consulting Agreement between the parties dated 5 April
1994.

      11.3 Amendment. This Agreement may be amended only by a written instrument
executed in one or more counterparts by the parties hereto.


                                      -7-


      11.4 Waiver. No consent to or waiver of any breach or default in the
performance of any obligation hereunder shall be deemed or construed to be a
consent to or waiver of any other breach or default in the performance of any of
the same or any other obligation hereunder. Failure on the part of either party
to complain of any act or failure to act of the other party or to declare the
other party in default, irrespective of the duration of such failure, shall not
constitute a waiver of rights hereunder and no waiver hereunder shall be
effective unless it is in writing, executed by the party waiving the breach or
default hereunder.

      11.5 Successors; Binding Agreement.

            11.5.1 Each of the Company and Vertex shall require any successor
(whether direct or indirect, by purchase, merger, consolidation or otherwise) to
all or substantially all of its business or assets to expressly assume and agree
to perform this Agreement in the same manner and to the same extent that it
would be required to perform it if no such succession had taken place. Failure
of the Company or Vertex to obtain such assumption and agreement prior to the
effectiveness of any such succession shall be a breach of this Agreement and
shall entitle the Executive to compensation from the Company, Vertex or their
respective successors in the same amount and on the same terms as he would be
entitled to hereunder if he terminates employment for Good Reason following a
Change in Control, except that for purposes of implementing the foregoing, the
date on which any such succession becomes effective shall be deemed the Date of
Termination. As used in this Agreement, "Company" and "Vertex" shall mean the
Company and Vertex, respectively, as hereinbefore defined and any successor to
its business or assets as aforesaid which assumes and agrees to perform this
Agreement by operation of law, or otherwise.

            11.5.2 This Agreement shall inure to the benefit of and be
enforceable by the Executive's personal or legal representatives, executors,
administrators, successors, heirs, distributees, devisees and legatees.

      11.6 Headings. The headings of sections and subsections of this Agreement
have been inserted for convenience of reference only and shall not be deemed to
be a part of this Agreement or to affect the meaning of any of its provision.

      11.7 Severability. If any provision of this Agreement shall, in whole or
in part, prove to be invalid for any reason, such invalidity shall affect only
the portion of such provision which shall be invalid, and in all other respects
this Agreement shall stand as if such invalid provisions, or the invalid portion
thereof, had not been a part hereof.

      11.8. Notices and Other Communications. All notices and other
communications required hereunder shall be in writing and personally delivered
or sent by certified mail, return receipt requested (a) if to the Executive at
Briar House, Bagwell Lane, Odiham, Hampshire, RG25 1JQ; and (b) if to the
Company, at 5 Cheapside Court, Buckhurst Road, Ascot, Berkshire, UK, SL5 7RF;
and (c) if to Vertex at 40 Allston Street, Cambridge, MA 02139-4211 USA,
attention: Chief Executive Officer; or in each case to such other persons or
addresses as the parties hereto may specify by a written notice to the other
from time to time. Such notices shall be effective four (4) business days after
so mailed or, if earlier, upon actual receipt. In order to be effective, any
notice of a purported termination of the Executive's employment by the Company
or by the Executive shall be communicated by writing to the other party in
accordance with this Section 11.8, indicating the specific termination provision
in this Agreement relied upon and setting forth in reasonable detail the facts
and circumstances claimed to provide a basis for termination of the Executive's
employment under the provision so indicated.


                                      -8-


12. STATUTORY PARTICULARS OF EMPLOYMENT.

The particulars required to be given to the Executive by Section 1 of the
Employment Protection (Consolidation) Act, 1978 and which are not given
elsewhere in this Agreement are set out in schedule 1 to this Agreement.

      IN WITNESS WHEREOF, this Agreement has been executed by the Company, by
its duly authorized officer, and by the Executive, as of the date first above
written.


VERTEX PHARMACEUTICALS                  EXECUTIVE:
(EUROPE) LIMITED


By: /s/ Richard H. Aldrich              /s/ Iain P.M. Buchanan
    ----------------------------        ----------------------------
    Richard H. Aldrich                  Iain P.M. Buchanan
    Director


VERTEX PHARMACEUTICALS
INCORPORATED


By: /s/ Joshua S. Boger
    ----------------------------
    Joshua S. Boger
    President and Chief Executive Officer


                                      -9-


                                   SCHEDULE 1

                       STATUTORY PARTICULARS OF EMPLOYMENT

1.    This Statement sets out the particulars required by Section 1 of the
      Employment Protection (Consolidation) Act 1978 relating to the employment
      by VERTEX PHARMACEUTICALS (EUROPE) LIMITED (the "Company"), of 5 Cheapside
      Court, Buckhurst Road, Ascot, Berkshire, SL5 7RF of IAIN P.M. BUCHANAN of
      Briar House, Bagwell Lane, Odiham, Hampshire, RG25 1JQ.

2.    PERIOD OF EMPLOYMENT

2.1   Your employment by the Company began on 3rd October, 1994. No previous
      period of employment is continuous with your employment by the Company.

2.2   Your employment is subject to termination by you or the Company upon
      notice as set forth in the attached Employment Agreement.

3.    JOB TITLE

3.1   Your job title is Vice President of European Operations of Vertex
      Pharmaceuticals Incorporated and and Managing Director of the Company.

3.2   In addition to the usual duties of a Managing Director, you may be
      required to undertake other duties, compatible with your status, from time
      to time to suit the Company's business needs.

3.3   You are required to report on a regular basis to the Board of the Company
      and the Board of Vertex Pharmaceuticals Inc. ("Vertex"), providing such
      details of your activities and other information as they may reasonably
      require, and to carry out, promptly, efficiently and to the best of your
      abilities all reasonable and lawful instructions which they may give you
      from time to time.

3.4   You must devote the whole of your time, attention and abilities during
      your hours of work to your duties for the Company. You may not, under any
      circumstances, whether directly or indirectly, undertake any other
      employment or engagement of any kind during the period of your employment
      by the Company.

4.    SALARY

4.1   Your basic salary is(pound)100,020 per annum.

4.2   Your salary will be paid monthly in arrears by credit transfer on or about
      the 25th day of each month.

4.3   Personal Performance-related bonus payments may be made from time to time
      at the Company's discretion.

5.    NORMAL HOURS OF WORK

5.1   Your normal hours of work are the Company's standard business hours from 8
      am to 5 pm each weekday together with such additional unpaid hours, either
      on weekdays or weekends, as may be necessary for the proper performance of
      your duties.


                                      -10-


6.    HOLIDAY ENTITLEMENT

6.1   The Company's holiday year is the calendar year from 1st January to 31st
      December. However, your holiday entitlement, during the one-year term of
      this appointment will be 20 working days' holiday in addition to the
      normal English public and Bank holidays. Your holiday must be taken during
      the holiday year and your holiday dates agreed in advance by the Board of
      Vertex and the Company

6.2   When your employment ceases, you will (unless your employment is
      terminated by the Company for Cause) be paid in lieu of any unused
      holiday. If you have taken too much holiday, you will be required to repay
      any salary received for additional holiday days. One day's holiday pay
      will be deemed to be 1/260th of your annual basic salary.

7.    CAR

7.1   You will be provided with a Company car for your business and personal use
      in accordance with and subject to the Company's car policy from time to
      time. The Company will bear all standing and running costs of the car but
      reserves the right in its absolute discretion to withdraw the use of the
      car from you at any time for any reason without compensation. You must, in
      any event, return the car to the Company's head office upon termination of
      your employment.

7.2   It is a condition of your employment that you have and keep a current
      driving licence. If you are disqualified from driving for any period, the
      Company reserves the right to dismiss you. If you commit any motoring
      offence or the car suffers or causes any accidental damage, you must
      notify the Company immediately.

8.    EXPENSES

8.1   The Company will reimburse to you all expenses properly incurred by you in
      the proper performance of your duties, provided that on request you
      provide the Company with such vouchers or other evidence of actual payment
      of such expenses as the Company may reasonably require.

9.    PENSION

9.1   You will be eligible to join the Vertex Personal pension scheme, subject
      to and in accordance with its trust deed and rules from time to time. The
      Company will contribute an amount equal to 10% of your salary and requires
      you to contribute 5% of your salary. You will hold the option to contract
      out of the State Earnings Related Pension Scheme (SERPS).

10.   OTHER BENEFITS

10.1  You will receive Private Health Insurance (BUPA) with subsidised rates for
      dependants.

10.2  You will be covered by the Company's death-in-service life assurance
      scheme for two times your annual basic salary including dependant's
      benefit of approximately four-ninths of basic salary.


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10.3  You will be granted a Stock Option over stock in Vertex under the terms of
      its 1991 Stock Option Plan on such terms as may be designated by the Board
      of Vertex. Details of your grant are outlined under a separate letter.

10.4  You will also be eligible to participate in the Vertex Employee Stock
      Purchase Plan on such terms as the Board of Vertex may decide. This will
      enable you to withdraw up to 10% of your net salary to purchase registered
      Vertex common stock at fair market value at the beginning or end of each
      six-month withholding period, whichever is the lower.

11.   PLACE OF WORK

11.1  Your normal place of work will be Cheapside Court, Ascot and/or any other
      UK place of business of the Company from time to time. You will be given
      at least one month's notice of any such change. The Company may, at its
      discretion, contribute towards any removal costs which you may incur
      should your place of work be changed to one which is more than fifty miles
      away from your previous place of work.

12.   CONFIDENTIALITY

12.1  You agree to treat as confidential all trade secrets and other
      confidential information relating to the Company's and Vertex's business
      and to sign and be bound by the terms of the Employee Non-Disclosure and
      Inventions Agreement, of which you have a copy.

12.2  You agree to return to the Company at the end of your employment all
      documents, computer disks and other items which belong to the Company or
      Vertex or relate to their business.

12.3  You will be responsible for the security of all keys, codes, electronic
      passes and combinations to security locks given to you by the Company to
      use in the course of your employment. You may not lend any of them or
      disclose combination numbers to any unauthorised person at any time after
      the end of your employment.

13.   SICKNESS ABSENCE

13.1  If you are unable to come to work for any reason and your absence has not
      been previously authorised by the Company, you must inform the Company
      immediately and keep the Company regularly informed of your progress and
      likely return date. For any absence of less than seven consecutive days,
      you are required to certify in writing the reasons for your absence. A
      doctor's certificate is required for all periods of absence in excess of
      seven days.

13.2  If you are absent from work due to sickness or injury and have complied
      with the requirements of clause 13.1. you will be paid:

      13.2.1 Your entitlement to Statutory Sick Pay ("SSP") (if any) in
             accordance with the provisions of the Social Security Contributions
             and Benefits Act 1992. For Statutory Sick Pay purposes your
             qualifying days are Monday to Sunday.

      13.2.2 Company Sick Pay (if the Company so decides from time to time),
             consisting of discretionary payments of all or part of your basic
             salary (less any entitlement to SSP and/or other state sickness
             benefits) for up to a maximum of 13 weeks'


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             absence in any 12-month period.

      13.2.3 An amount equal to any sums receivable by the Company, as a result
             of your absence, under the terms of its permanent health insurance
             scheme.

14.   DISCIPLINARY & GRIEVANCE PROCEDURE

14.1  There are no particular disciplinary rules or procedures applicable to you
      and you are expected to conduct yourself in a thoroughly professional
      manner at all times. If you have any grievance relating to your
      employment, you should raise the matter with the Board of the Company,
      whose decision will be final and binding on you.

15.   HEALTH & SAFETY AT WORK

15.1  The Company will take all reasonably practicable steps to ensure your
      health, safety and welfare when at work. In the interests of all
      employees, the Company operates a no-smoking policy.

16.   MISCELLANEOUS

16.1  The Company reserves the right to make reasonable changes to any of your
      terms and conditions of employment.

16.2  The Company has the right to deduct from your pay any sums which you may
      owe the Company, and you agree to the Company making such deductions.

16.3  There are no collective agreements in force which directly affect your
      terms and conditions of employment.

16.4  The Company has no immediate requirement for you to work outside the
      United Kingdom for a period of one month or more.

16.5  The terms and conditions of your employment shall be governed by and
      construed in accordance with English law.


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