Document:

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                                                                   Exhibit 10.50

May 14, 2001

Mr. Richard Nanula
26901 Pacific Coast Highway
Malibu, California 90265

Dear Richard:

I am pleased to offer you the position of Executive Vice President, Finance,
Strategy and Communications, salary grade E38, reporting to me.  You will become
Chief Financial Officer of Amgen Inc. on August 1, 2001.

Base Salary and Annual Incentive
--------------------------------

Your monthly salary will be $50,000.  As an Executive Vice President, you will
be eligible to participate in Amgen's Management Incentive Plan (the "MIP")
pursuant to the terms of the MIP.  Your annual target incentive opportunity will
be 70% of your base salary earnings during the year.  Your performance against
pre-established goals and Amgen's performance will determine your actual
incentive each year.  We will guarantee a prorated 70% of your 2001 base salary
earnings (dependent upon your start date in 2001) as a bonus for 2001 or the
actual results from MIP, whichever is greater. You must be actively employed by
Amgen on December 31, 2001 to receive the guaranteed payments for 2001.

Stock Options
-------------

Subject to the approval of the Compensation Committee of the Amgen Board of
Directors, you will be granted an option to purchase 200,000 shares of Amgen's
common stock at a price equal to 100% of the fair market value on the date of
grant which will be the later of your start date or the date of approval by the
Compensation Committee.  This option shall be an incentive stock option to the
extent permitted by law, with the balance being granted as a non-qualified stock
option.  This option shall be vested at a rate of 25% per year for four years,
beginning one year from the date of grant, and the option will expire seven
years from the date of grant, subject to earlier expiration in connection with
the termination of your employment with Amgen.  The option will be granted
pursuant to, and in conformity with, the terms of Amgen's Amended and Restated
1991 Equity Incentive Plan.

In addition, you will also be eligible to receive additional stock options as
part of Amgen's Periodic Stock Option Program (the "PSOP").  Grants under the
PSOP are discretionary and are usually made in July of each year, as approved by
Amgen's Compensation Committee.  However, for 2001 and 2002, subject to approval
by the Compensation Committee of Amgen's Board of Directors, Amgen will grant
you an option to purchase 150,000 shares in each of these years.  These options
will be granted pursuant to, and in conformity with, the terms of the PSOP.
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These PSOP options will vest 20% per year for five years, beginning one year
from the date of grant, and the options will expire seven years from the date of
grant, subject to earlier expiration in connection with the termination of your
employment with Amgen.  You must be actively employed by Amgen on the PSOP grant
date in each year to receive the PSOP grant for that year.

Restricted Stock
----------------

In lieu of a signing bonus and the annual retention bonuses that we have
previously discussed, Amgen will award you 85,000 shares of restricted stock
under Amgen's Amended and Restated 1991 Equity Incentive Plan on the later of
your start date or the date of approval by the Compensation Committee in
consideration of your payment of the $.0001 per share par value of the
restricted shares (the "Par Value Price"), in the aggregate amount of $8.50.
This grant is being made for retention purposes and to tie your financial
success to the financial success of our shareholders.  This grant will vest as
follows, contingent upon your being actively employed with Amgen on each vesting
date:

     May 16, 2004       20,000 shares

     May 16, 2005       20,000 shares

     May 16, 2006       45,000 shares

Upon the termination of your active employment with Amgen, any unvested shares
of restricted stock will be forfeited, except that upon termination of your
employment due to your "Permanent and Total Disability," as defined below, or
your death, then the vesting of the unvested shares of restricted stock will be
accelerated so that all the restricted stock will be fully vested as of the date
of termination. For the purposes of this provision, you shall have incurred a
"Permanent and Total Disability" when such a disability has been certified by
the Social Security Administration prior to the date of termination.  Amgen will
hold the certificates representing any unvested shares of restricted stock until
the shares vest, at which time Amgen will issue you a certificate representing
the vested shares.  Upon the forfeiture of any of the restricted shares, Amgen
will pay you an amount equal to the Par Value Price for each forfeited share.

Loan
----

Within 30 days after your start date, Amgen will loan you $3,000,000 which will
be evidenced by your unsecured promissory note.  Interest will accrue on the
loan at the rate of 5% and will be compounded and payable annually. Principal
and any accrued and unpaid interest will be due and payable 9 years after the
date the loan is made, subject to acceleration upon the termination of your
employment with Amgen for any reason.

Termination
-----------

If, within the first five years of your employment with Amgen, either: (i) Amgen
terminates your employment without Cause, as defined below, or (ii) you resign
your employment due to a reduction of your duties or your base salary or annual
target incentive opportunity under the MIP, then you will be entitled to three
years of base salary and target incentive paid monthly and health care coverage
unless coverage is obtained from another employer, but only if you sign a
general release form furnished to you by Amgen.  If you intend to resign your
employment for reduction of duties or compensation, you must notify the Company
in writing.  If Amgen fails to cure or remedy your reason for resignation within
thirty (30) days of its receipt of your
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notification and you still choose to resign, you must do so within fifteen (15)
days of Amgen's failure to cure or remedy your reason. If you are also entitled
to receive severance benefits under the Amgen Inc. Change of Control Severance
Plan (the "COC Plan") on account of a termination covered by this provision, you
will be paid the greater of the amount provided above or provided in the COC
Plan, but not both amounts.

Solely for the purpose of this provision, "Cause" means (i) your conviction of a
felony,  (ii) the engaging by you in conduct that constitutes willful gross
neglect or willful gross misconduct in carrying out your duties to Amgen,
resulting, in either case, in material economic harm to Amgen, unless you
believed in good faith that such conduct was in, or not contrary to, the best
interests of Amgen, (iii) your material breach of any of the terms of this
letter agreement or the Proprietary Information and Inventions Agreement or (iv)
your failure to follow any lawful directive of Amgen's Chief Executive Officer
with respect to your employment.  For purposes hereof, no act, or failure to
act, on your part shall be deemed "willful" unless done, or omitted to be done,
by you not in good faith.

Benefits
--------

You will also have the opportunity to participate in our comprehensive benefits
program.  Amgen's excellent health care plan currently includes medical, dental,
and vision coverage for you and your eligible dependents.  Amgen currently pays
the major expense for these programs while staff members share through payroll
deductions.  Please be advised that in order for you and your dependents to be
eligible for Amgen's medical coverage you must:

    1.  Report to work at Amgen or another location to which you are required to
        travel and perform the regular duties of your employment.

    2.  Contact the Amgen Benefit Center at Fidelity, 1-877-999-7779, to enroll
        within 31 days of your hire date.

    3.  Meet all other eligibility requirements under the plan.

Amgen's Retirement & Savings 401(K) Plan provides an opportunity for staff
members to save up to 15% of their pay on a tax deferred basis. (Maximum
statutory individual limit for 2001 will be $10,500).  Amgen will also
contribute to your 401(K) account to help you save for your future financial
goals.  The benefits, services and programs are summarized in the enclosed
brochure called "A Guide to Your Pay and Benefits."  You will also be eligible
for Amgen's Supplemental (401K) Retirement Plan (the "SRP").

You will also be entitled to senior executive physicals, financial counseling
and tax preparation services at the same level as all other Amgen senior
executives.  When you travel on Amgen business, you may travel first class,
provided that you make arrangements for such travel with Amgen's designated
travel agents and pursuant to Amgen's travel and business expense policies.  You
will be responsible for paying all applicable income and employment taxes on
your Amgen compensation and benefits and will be subject to all income and
employment tax withholding.

Required Documents
------------------

Enclosed and included as part of this offer (Attachment) is information
regarding Amgen's Proprietary Information and Inventions Agreement, the
Immigration Reform & Control Act, and a packet of materials entitled
"Arbitration of Disputes - Amgen Inc." which includes a Mutual
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Agreement to Arbitrate Claims. This offer is contingent upon your completing the
items described in the Attachment.

Employment At Will
------------------

By signing this letter, you understand and agree that your employment with Amgen
is at-will.  Therefore, your employment can terminate, with or without Cause,
and with or without notice, at any time, at your option or Amgen's option, and
Amgen can terminate or change all other terms and conditions of your employment,
with or without Cause, and with or without notice, at any time.  This at-will
relationship will remain in effect throughout your employment with Amgen Inc. or
any of its subsidiaries, or affiliates.  This letter, including the documents
contained in the Attachment, constitutes the entire agreement, arrangement and
understanding between you and Amgen on the nature and terms of your employment
with Amgen.  This letter supersedes any prior or contemporaneous agreement,
arrangement or understanding on this subject matter, including our prior letter
agreement dated April 27, 2001.  By executing this letter as provided below, you
expressly acknowledge the termination of any such prior agreement, arrangement
or understanding.  Also, by your execution of this letter, you affirm that no
one has made any written or verbal statement that contradicts the provisions of
this letter.  The at-will nature of your employment, as set forth in this
paragraph, can be modified only by a written agreement signed by both Amgen's
Chief Executive Officer and you which expressly alters it.  This at-will
relationship may not be modified by any oral or implied agreement, or by any
Company policies, practices or patterns of conduct.

You have made an excellent impression on us.  We are enthusiastic about you
joining our executive management team and the contributions you can make to
Amgen.  Please retain the original offer letter for your records and return the
signed copy and required documents to me.  If you have any questions, please
contact John Hillins in the office at (805) 447 -7456 or (805) 480-3519 at home.

Sincerely,

/s/ Kevin Sharer

/s/ Richard Nanula          5/15/01
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Signature of Acceptance      Date
Enclosures<PAGE>

                                                                   Exhibit 10.51

                                PROMISSORY NOTE
                                ---------------

$3,000,000.00

1.  Promise to Pay.
    --------------

    For value received, I, Richard Nanula ("Staff Member"), promise to pay to
    the order of Amgen Inc., a Delaware corporation ("Amgen" or "Payee"), at its
    office at One Amgen Center Drive, Thousand Oaks, CA 91320-1799, the sum of
    Three Million Dollars and No Cents ($3,000,000.00) (the "Principal"),
    payable in full on the earlier of: (i) nine (9) years from the date of
    execution of this Promissory Note (this "Note"); (ii) thirty (30) days from
    the date on which Staff Member resigns of his own accord; or (iii) thirty
    (30) days from the date on which Staff Member is terminated by Payee for
    Cause (as defined below), whichever first occurs.  Such payment shall
    include any interest on the Principal from the date of the last interest
    payment until such date as this Note is paid in full.

    Should Payee terminate Staff Member without Cause, this Note will become
    payable in equal annual payments over the lesser of: (i) five (5) years; or
    (ii) the remainder of the original nine (9) year term of this Note.  The
    payments shall be due annually on the anniversary date of Staff Member's
    departure and shall include both Principal and interest on the Principal
    from the date of the last interest payment until such date as this Note is
    paid in full.

    Interest on this Note shall be payable in equal annual payments commencing
    on the anniversary date of the funding of the loan and each successive year
    thereafter until the Principal is repaid.  The interest rate of this Note is
    5.0% per annum on the Principal.

2.  Cause.
    -----

    "Cause" means: (i) Staff Member's conviction of a felony; (ii) the engaging
    by Staff Member in conduct that constitutes willful gross neglect or willful
    gross misconduct in carrying out Staff Member's duties to Amgen, resulting,
    in either case, in material economic harm to Amgen, unless Staff Member
    believed in good faith that such conduct was in, or not contrary to, the
    best interests of Amgen; (iii) Staff Member's material breach of any of the
    terms of the letter agreement between Staff Member and Amgen dated May 14,
    2001 or the Proprietary Information and Inventions Agreement; or (iv) Staff
    Member's failure to follow any lawful directive of Amgen's Chief Executive
    Officer with respect to Staff Member's employment.  For purposes hereof, no
    act, or failure to act, on Staff Member's part shall be deemed "willful"
    unless done, or omitted to be done, by Staff Member not in good faith.

3.  Prepayment.
    ----------

    Staff Member may prepay without penalty this Note in whole or in part at any
    time.  Any and all payments or prepayments under this Note may be made by
    Staff Member to Payee at the following address (or such other address as it
    designates in writing to Staff Member):

                AMGEN INC.
                One Amgen Center Drive
                Thousand Oaks, California 91320-1799

                Attention:  Accounting Manager
<PAGE>

4.  Attorneys' Fees.
    ---------------

    Staff Member agrees to pay all costs and expenses, including, without
    limitation, collection agency fees and expenses, reasonable attorneys' fees,
    costs of suit and costs of appeal, which Payee may incur in the exercise,
    preservation or enforcement of its right, powers and remedies hereunder, or
    under any documents or instruments securing this Note, or under law.

5.  Modification of Terms.
    ---------------------

    Payee may, with or without notice to Staff Member, cause additional parties
    to be added to this Note, or release any party to this Note, or revise,
    extend, or renew this Note, or extend the time for making any installment
    provided for by this Note, or accept any installment in advance, all without
    affecting the liability of Staff Member.  Staff Member may not assign or
    transfer in any manner whatsoever this Note or any of Staff Member's
    obligations under this Note without Payee's written consent.

6.  Acceleration.
    ------------

    A) In the event Staff Member fails to pay when due any sums under this Note,
    then:

       (i) the entire unpaid balance of this Note shall, at the option of the
       Payee hereof, immediately become due and payable in full and unpaid
       Principal thereafter shall bear interest at the lesser of the maximum
       rate permitted by law or at the rate of 8.0% per annum; and

       (ii) Staff Member authorizes Payee to deduct any sums due to Payee under
       this Note from any monies, including any wages due, otherwise owing to
       Staff Member.

7.  Waiver of Rights by Staff Member.
    --------------------------------

    Staff Member waives: (i) presentment, demand, protest, notice of dishonor
    and/or protest and notice of non-payment; and (ii) the right to require the
    Payee to proceed against any party to this Note, or to pursue any other
    remedy in Payee's power.  Payee may proceed against Staff Member directly
    and independently of any other party to this Note, and the cessation of the
    liability of any other party for any reason other than full payment, or any
    revision, renewal, extension, forbearance, change of rate of interest, or
    any impairment or suspension of Payee's remedies or rights against any other
    party, shall not in any way affect the liability of Staff Member.

8.  Successors and Assigns.
    ----------------------

    This Note shall be binding on Staff Member's heirs, administrators,
    representatives, executors, successors and assigns.

9.  Governing Law.
    -------------

    This Note and the obligations of Staff Member under this Note shall be
    governed by and interpreted and determined in accordance with the laws of
    the State of California as applied

                                       2
<PAGE>

    to contracts between California residents entered into and to be performed
    entirely within said State.

IN WITNESS WHEREOF, the undersigned has executed and delivered this Note as of
the    27th    day of    June   , 2001.
    ----------        ----------

                                          /s/  Richard Nanula
                                          -------------------
                                          Richard Nanula

                                       3

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