EXHIBIT 10.1

PHARMACYCLICS, INC.

NOVEMBER 5, 2008

David Loury, Ph.D.
Vice President, Pre-Clinical Sciences
Pharmacyclics, Inc.
995 East Arques Avenue
Sunnyvale, CA 94086

Dear David:

The purpose of this letter agreement (this "Agreement") is to document the terms
of the severance payment to which you will be entitled should your employment
with Pharmacyclics, Inc. (the "Company") be terminated involuntarily.

Part One of this Agreement specifies the terms and conditions of your severance
benefit. Part Two sets forth certain definitional provisions to be in effect for
purposes of determining your benefit entitlements. Part Three concludes this
Agreement with a series of general terms and conditions applicable to your
benefit.

PART ONE — SEVERANCE BENEFIT

Upon any Involuntary Termination effected during the term of this Agreement, you
will become entitled to receive the special severance benefit set forth below.

Severance Payment

. You will receive a severance payment from the Company following your
Involuntary Termination that is not a Termination for Cause in an aggregate
amount equal to the annual rate of base salary in effect for you at the time of
your Involuntary Termination, provided that you execute a release of all claims
arising out of your employment with the Company, or the termination thereof, in
a form reasonably acceptable to the Company, within fifty (50) days following
the date of your Involuntary Termination and you do not revoke such release
within any period permitted under applicable law. The severance payment shall be
paid to you over the twelve months following the date of your Involuntary
Termination in equal installments in accordance with the Company's normal
payroll practices. However, the payments shall not commence until the release
described above has become effective and irrevocable (the "
Release Effective Date
"), and any installment payments that would have been made to you prior to the
Release Effective Date shall be paid to you on the Company's first payroll date
following the Release Effective Date and the remaining payments shall be made as
provided in this Agreement. Any payment under this Paragraph 1 will be subject
to the Company's collection of applicable withholding taxes.

Restrictive Covenants

. For the twelve (12) month period following your Involuntary Termination:

You will not directly or indirectly encourage or solicit any individual to leave
the Company's employ for any reason or interfere in any other manner with the
employment relationships at the time existing between the Company and its
current or prospective employees.

You will not induce or attempt to induce any customer, supplier, distributor,
licensee or other business relation of the Company to cease doing business with
the Company or in any way interfere with the existing business relationship
between any such customer, supplier, distributor, licensee or other business
relation and the Company.

You will not in any manner, forum or media, defame or intentionally make,
publish or disseminate, disparaging remarks regarding the Company or its
affiliates, except as may be required by applicable law.

PART TWO — DEFINITIONS

Definitions

. For purposes of this Agreement, the following definitions will be in effect:

Board

means the Company's Board of Directors.

Involuntary Termination

means your "separation from service" with the Company involuntarily upon your
discharge or dismissal by the Company. In no event shall an Involuntary
Termination be deemed to occur should your employment terminate by reason of
death or permanent disability.

Termination for Cause

means an Involuntary Termination of your employment with the Company by reason
of your commission of any act of fraud, embezzlement or dishonesty, or your
unauthorized use or disclosure of confidential information or trade secrets of
the Company or its subsidiaries or your material failure to perform your duties
as specified by the Chief Executive Officer of the Company or the Board.

PART THREE — MISCELLANEOUS PROVISIONS

1.

Termination for Cause. Notwithstanding anything in this Agreement to the
contrary, should your Involuntary Termination constitute a Termination for
Cause, then the Company shall only be required to pay you (i) any unpaid
compensation earned for services previously rendered through the date of such
termination and (ii) any accrued but unpaid vacation benefits or sick days, and
no benefits will be payable to you under Part One of this Agreement.

2. General Creditor Status

. The benefits to which you may become entitled under this Agreement will be
paid, when due, from the general assets of the Company. Your right (or the right
of the executors or administrators of your estate) to receive any such payments
will at all times be that of a general creditor of the Company and will have no
priority over the claims of other general creditors of the Company.

3. Miscellaneous

. The provisions of this Agreement will be construed and interpreted under the
laws of the State of California. This Agreement incorporates the entire
agreement between you and the Company relating to the subject of severance
benefits and supersedes all prior agreements and understandings with respect to
such subject matter (provided, however, that you shall continue to be entitled
to any acceleration of vesting of an option to purchase shares of the Company's
common stock or any unvested issuance of shares of the Company's common stock
pursuant to the terms of the agreement between you and the Company evidencing
such award or the applicable equity plan of the Company under which the award
was granted). This Agreement may only be amended by written instrument signed by
you and another duly-authorized officer of the Company. If any provision of this
Agreement as applied to any party or to any circumstance should be adjudged by a
court of competent jurisdiction to be void or unenforceable for any reason, the
invalidity of that provision shall in no way affect (to the maximum extent
permissible by law) the application of such provision under circumstances
different from those adjudicated by the court, the application of any other
provision of this Agreement, or the enforceability or invalidity of this
Agreement as a whole. Should any provision of this Agreement become or be deemed
invalid, illegal or unenforceable in any jurisdiction by reason of the scope,
extent or duration of its coverage, then such provision shall be deemed amended
to the extent necessary to conform to applicable law so as to be valid and
enforceable or, if such provision cannot be so amended without materially
altering the intention of the parties, then such provision shall be stricken and
the remainder of this Agreement shall continue in full force and effect.

4. Remedies

. All rights and remedies provided pursuant to this Agreement or by law will be
cumulative, and no such right or remedy will be exclusive of any other. A party
may pursue any one or more rights or remedies hereunder or may seek damages or
specific performance in the event of another party's breach hereunder or may
pursue any other remedy by law or equity, whether or not stated in this
Agreement.

5. Arbitration

. Any controversy which may arise between you and the Company with respect to
the construction, interpretation or application of any of the terms, provisions
or conditions of this Agreement or any monetary claim arising from or relating
to this Agreement will be submitted to final and binding arbitration in San
Jose, California in accordance with the rules of the American Arbitration
Association then in effect.

6. No Employment or Service Contract

. Nothing in this Agreement shall confer upon you any right to continue in the
employment of the Company for any period of specific duration or interfere with
or otherwise restrict in any way the rights of the Company or you, which rights
are hereby expressly reserved by each, to terminate your employment at any time
for any reason whatsoever, with or without cause.

[Signature page follows]

Please indicate your acceptance of the foregoing provisions of this Agreement by
signing the enclosed copy of this Agreement and returning it to the Company.

PHARMACYCLICS, INC.

By: /s/ ROBERT W. DUGGAN
     Robert W. Duggan
     Chairman and Interim CEO

ACCEPTED BY AND AGREED TO

Signature: /s/ DAVID LOURY
                 David Loury

Dated:November 5, 2008