<PAGE>

                         EXECUTIVE EMPLOYMENT AGREEMENT

          THIS EXECUTIVE EMPLOYMENT AGREEMENT (this "Agreement") is made and
entered into as of this 5th day of January, 2000, effective as of the 5th day of
January, 2000 (the latter date shall be referred to as the "Effective Date"), by
and between ALEXANDRIA REAL ESTATE EQUITIES, INC., a Maryland corporation
("Corporation"), and Laurie A. Allen, an individual ("Officer") (hereinafter,
Corporation and Officer will be referred to collectively as the "Parties").

                                     RECITAL

          WHEREAS, Corporation desires to employ Officer as its Senior Vice
President - Business Development and Legal Affairs and Secretary, and Officer is
willing to accept such employment by Corporation, on the terms and subject to
the conditions set forth in this Agreement; and

          WHEREAS, this Agreement shall be subject to the approval of the
Compensation Committee, which is expected no later than February 14, 2000.

          NOW, THEREFORE, in consideration of the mutual covenants contained
herein and other good and valuable consideration, the receipt and sufficiency of
which is hereby acknowledged, the Parties hereto agree as follows:

1. POSITION AND DUTIES; LOCATION.

          During the Term (as defined below) of this Agreement, Officer agrees
to be employed by and to serve Corporation as its Senior Vice President -
Business Development and Legal Affairs and Secretary. Corporation agrees to
employ and retain Officer in such capacities. Officer shall devote her full
business time, energy, and skill to the affairs of Corporation. Notwithstanding
the foregoing, Officer shall be entitled to consult not more than fifteen (15)
hours per month for ARIAD Pharmaceuticals, Inc. Officer shall report to the
Chief Executive Officer of the Corporation or such other officer as the Chief
Executive Officer shall direct. Officer shall be based at Corporation's office
in Pasadena, California.




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2. TERM OF EMPLOYMENT.

                  The Term of this Agreement shall commence on the Effective
Date and shall continue until December 31, 2000 (the "Term"); PROVIDED, HOWEVER,
that on December 31, 2000, and on each anniversary thereof, the Term of this
Agreement shall automatically be extended for one (1) additional year unless,
not later than ninety (90) days prior to such date, either party shall have
given written notice to the other that it does not wish to extend the Term of
the Agreement. If Officer's employment hereunder shall terminate by reason of
the expiration of the Term (including any extensions thereof), the date of such
termination shall be referred to as the "Termination Date."

3. COMPENSATION, BENEFITS AND REIMBURSEMENT.

          3.1. BASE SALARY. During the Term of this Agreement and subject to the
terms and conditions set forth herein, Corporation agrees to pay to Officer an
initial annual "Base Salary" of two hundred and fifteen thousand dollars
($215,000), or such other amount as may from time-to-time be determined by
Corporation. Unless otherwise agreed in writing by Officer and Corporation, the
Base Salary shall be payable in substantially equal semimonthly installments in
accordance with the standard policies of Corporation in existence from
time-to-time.

          3.2. ADJUSTMENTS IN BASE SALARY. Officer's Base Salary shall be
reviewed for the possibility of upward adjustments no less frequently than on
each anniversary of the Effective Date during the Term of this Agreement.

          3.3. RELOCATION REIMBURSEMENT. Officer shall be entitled to receive
reimbursement for relocating to Los Angeles, California, in an amount equal to
and no greater than $35,000, such reimbursement shall be earned, due and payable
on April 1, 2000.

          3.4. DISCRETIONARY BONUS. If Officer is in good standing, as finally
determined by the Chief Executive Officer with the concurrence of the Board of
Directors ("Board"), Officer shall be eligible to receive a discretionary bonus
for each fiscal year of Corporation during the Term of this Agreement, with the
actual amount of any such bonus to be determined by the Chief Executive Officer
with the concurrence of the Board (or a committee of the Board) based upon an
evaluation of Officer's and Corporation's performance during such year and such
other factors and conditions as the Board (or a committee of the Board) deems
relevant.



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<PAGE>

          3.5. STOCK OPTIONS. Subject to the approval of the Board (or a
committee of the Board) and pursuant to the terms of a stock option agreement
issued under a stock option plan of the Corporation, Corporation shall grant to
Officer the right and option to purchase 70,000 shares of the authorized but
unissued Common Stock of Corporation on the terms and conditions set forth
therein. Nothing contained herein shall be construed to increase or decrease
Officer's compensation and/or benefits in existence at the time the options are
granted.

          3.6. ADDITIONAL BENEFITS. Officer shall be entitled to the following
additional benefits under this Agreement:

          (a) OFFICER BENEFITS. During the Term of this Agreement, Officer shall
be eligible to participate in Corporation's existing medical plan and 401(k)
plan and such existing stock incentive plans available to senior management of
the Corporation in accordance with the terms and conditions of such plans.
During the Term of this Agreement, Corporation shall pay one hundred percent
(100%) of Officer's medical premiums under Corporation's medical plan and any
other welfare benefit plans for which Officer qualifies that are in existence
from time to time.

          (b) VACATION. During the Term of this Agreement, Officer shall be
entitled to up to four (4) weeks paid vacation annualized during each calendar
year during the Term of this Agreement. Limits on accrual of vacation not taken
during any calendar year shall be subject to and in accordance with
Corporation's existing policy.

          (c) REIMBURSEMENT FOR EXPENSES. During the Term of this Agreement,
Corporation shall reimburse Officer for all reasonable out-of-pocket business
and/or entertainment expenses incurred by Officer for the purpose of and in
connection with the performance of her services pursuant to this Agreement and
in accordance with any existing travel and expense reimbursement policies of
Corporation. Officer shall be entitled to such reimbursement upon the
presentation by Officer to Corporation of vouchers or other statements itemizing
such expenses in reasonable detail consistent with Corporation's policies. In
addition, Officer shall be entitled to reimbursement for (i) dues and membership
fees in professional organizations and/or industry associations in which Officer
is currently a member or becomes a member, and (ii) appropriate industry
seminars and mandatory continuing education.



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<PAGE>

          (d) WITHHOLDING. Compensation and benefits paid to Officer under this
Agreement shall be subject to applicable federal, state and local wage
deductions and other deductions required by law.

4. TERMINATION OF THE AGREEMENT.

          4.1. TERMINATION WITHOUT CAUSE. In the event that Corporation
terminates this Agreement without Cause (as defined below), Officer shall be
entitled to a severance payment equal to nine (9) months ("Severance Period") of
Officer's annualized Base Salary ("Severance Payment"). Such Severance Payment
shall be payable in monthly installments during the Severance Period, in
accordance with the provisions set forth in Paragraph 3.1 above. Officer shall
not be entitled to receive a Severance Payment hereunder if she voluntarily
terminates her employment or is terminated by reason of death or disability or
for Cause.

          4.2. TERMINATION FOLLOWING A CHANGE IN CONTROL. In the event that
Corporation terminates this Agreement without Cause (as defined below) following
a Change in Control (as defined below), Corporation shall pay Officer the
Severance Payment, in accordance with Paragraph 4.1 above, and provide for
immediate and full vesting of any stock options granted to Officer under
Corporation's stock option plan. For purposes of this Agreement, a "Change in
Control" shall be deemed to have occurred if:

     (i) Any Person, as such term is used in section 3(a)(9) of the Securities
Exchange Act of 1934, as amended from time-to-time (the "Exchange Act"), as
modified and used in sections 13(d) and 14(d) thereof, (other than (A) the
Corporation or any of its subsidiaries, (B) a trustee or other fiduciary holding
securities under an employee benefit plan of the Corporation or any of its
affiliates, (C) an underwriter temporarily holding securities pursuant to an
offering of such securities, (D) a corporation owned, directly or indirectly, by
the stockholders of the Corporation in substantially the same proportions as
their ownership of stock of the Corporation, or (E) a person or group as used in
Rule 13d-1(b) under the Exchange Act) is or becomes the Beneficial Owner, as
such term is defined in Rule 13d-3 under the Exchange Act, directly or
indirectly, of securities of the Corporation (not including in the securities
beneficially owned by such Person any securities acquired directly from the
Corporation or its affiliates other than in connection with the acquisition by
the Corporation or its affiliates of a business) representing twenty-five
percent (25%) or more of the combined voting power of the Corporation's then
outstanding securities; or


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     (ii) The following individuals cease for any reason to constitute a
majority of the number of directors then serving: individuals who, on the date
hereof, constitute the Board and any new director (other than a director whose
initial assumption of office is in connection with an actual or threatened
election contest, including but not limited to a consent solicitation, relating
to the election of directors of the Corporation) whose appointment or election
by the Board or nomination for election by the Corporation's stockholders was
approved or recommended by a vote of at least two-thirds (2/3) of the directors
then still in office who either were directors on the date hereof or whose
appointment, election or nomination for election was previously so approved or
recommended; or

     (iii) There is consummated a merger or consolidation of the Corporation
with any other corporation, other than (A) a merger or consolidation which would
result in the voting securities of the Corporation outstanding immediately prior
to such merger or consolidation continuing to represent (either by remaining
outstanding or by being converted into voting securities of the surviving entity
or any parent thereof), in combination with the ownership of any trustee or
other fiduciary holding securities under an employee benefit plan of the
Corporation or any subsidiary of the Corporation, at least seventy-five percent
(75%) of the combined voting power of the securities of the Corporation or such
surviving entity or any parent thereof outstanding immediately after such merger
or consolidation, or (B) a merger or consolidation effected to implement a
recapitalization of the Corporation (or similar transaction) in which no Person
is or becomes the Beneficial Owner, directly or indirectly, of securities of the
Corporation (not including in the securities beneficially owned by such Person
any securities acquired directly from the Corporation or its affiliates other
than in connection with the acquisition by the Corporation or its affiliates of
a business) representing twenty-five percent (25%) or more of the combined
voting power of the Corporation's then outstanding securities; or

     (iv) The stockholders of the Corporation approve a plan of complete
liquidation or dissolution of the Corporation or there is consummated an
agreement for the sale or disposition by the Corporation of all or substantially
all of the Corporation's assets, other than a sale or disposition by the
Corporation of all or substantially all of the Corporation's assets to an
entity, at least seventy-five (75%) of the combined voting power of the voting
securities of which are owned by stockholders of the Corporation in
substantially the same proportions as their ownership of the Corporation
immediately prior to such sale.




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          4.3. TERMINATION FOR CAUSE. Prior to the Termination Date, the
Corporation shall have the right to terminate this Agreement for Cause
immediately after written notice has been delivered to Officer, which notice
shall specify the reason for and the effective date of such Termination. For
purposes of this Agreement, "Cause" shall mean the following:

     (i)  Officer's Material breach, repudiation or failure to comply with or
          perform (a) any of the terms of this Agreement, (b) any of Officer's
          duties, or (c) any of Corporation's policies or procedures (including
          without limitation any such policies or procedures relating to
          conflicts of interests or standards of business conduct); or Officer's
          deliberate interference with the compliance by any other employee of
          Corporation with any of the foregoing; or

     (ii) The conviction of Officer for, or pleading by Officer of no contest
          (or similar plea) to, fraud, embezzlement, misappropriation of assets,
          malicious mischief, or any felony, other than a crime for which
          vicarious liability is imposed upon Officer solely by reason of
          Officer's position with Corporation and not by reason of Officer's
          conduct.

          Before terminating the Agreement pursuant to this Paragraph 4.3(i),
Corporation first shall have given Officer written notice specifying the nature
of the breach, repudiation or failure to comply and thirty (30) days thereafter
in which to cure such Material breach, repudiation or failure to comply, and
Officer shall have failed to cure. For purposes of this Paragraph 4.3,
"Material" shall mean a breach, repudiation or failure that the Board determines
has resulted in material injury to Corporation.

          4.4. OFFSET. Although Officer shall not be required to mitigate
damages under this Agreement by seeking other comparable employment or
otherwise, the amount of any payment or benefit provided for in this Agreement
shall be reduced by any compensation earned by or provided to Officer as the
result of employment by an employer other than Corporation prior to the
expiration of the Term of this Agreement.




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5. NONCOMPETITION.

                  During the Term of this Agreement, including the period, if
any, with respect to which Officer shall be entitled to Severance Payments,
Officer shall not engage in any activity that is or may be competitive with the
business of Corporation, directly or indirectly, whether or not for
compensation, including, but not limited to, providing services similar to those
provided by the Company; offering or soliciting or accepting an offer, to
provide such services or taking any action to form, or become employed by, a
firm or business to provide such services.

6. MISCELLANEOUS.

          6.1. CONFIDENTIALITY. Without limiting the scope of the Agreement
Regarding Proprietary Information between the Parties, dated as of January 5,
2000 (the "Proprietary Information Agreement"), Officer agrees that all
confidential and proprietary information relating to the business of Corporation
shall be kept and treated as confidential both during and after the Term of this
Agreement, except as may be permitted in writing by the Board or as such
information is within the public domain or comes within the public domain
without any breach of this Agreement.

          6.2. WAIVER. The waiver of the breach of any provision of this
Agreement shall not operate or be construed as a waiver of any subsequent breach
of the same or other provision hereof.

          6.3. ENTIRE AGREEMENT; MODIFICATIONS. Except as otherwise provided
herein, this Agreement (together with the Proprietary Information Agreement and
any other agreements and plans referred to herein) represents the entire
understanding between the Parties with respect to the subject matter hereof, and
this Agreement supersedes any and all prior understandings, agreements, plans
and negotiations, whether written or oral, with respect to the subject matter
hereof, including without limitation any understandings, agreements or
obligations respecting any past or future compensation, bonuses, reimbursements
or other payments to Officer from Corporation. All modifications to this
Agreement must be in writing and signed by the party against whom enforcement of
such modification is sought.




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          6.4. NOTICES. All notices and other communications under this
Agreement shall be in writing and shall be given by facsimile or first-class
mail, certified or registered with return receipt requested, and shall be deemed
to have been duly given three (3) days after mailing or twenty-four (24) hours
after transmission of a facsimile to the respective persons named below:

          If to Corporation:        Alexandria Real Estate Equities, Inc.
                                    135 North Los Robles Avenue, Suite 250
                                    Pasadena, CA  91101
                                    Phone:   (626) 578-0777
                                    Facsimile:      (626) 578-0770
                                    Attn:   Joel S. Marcus, CEO

          If to Officer:            Laurie A. Allen
                                    357 Comstock Avenue
                                    Los Angeles, CA 90024
                                    Phone:   (310) 441-9576

          6.5. HEADINGS. The Paragraph headings herein are intended for
reference only and shall not determine the construction or interpretation of
this Agreement.

          6.6. GOVERNING LAW. This Agreement shall be governed by and construed
in accordance with the laws of the State of California without regard to its
principles of conflicts of laws.

          6.7. ARBITRATION. Any dispute arising out of or relating to this
Agreement that cannot be settled by good faith negotiation between the Parties
shall be submitted to ENDISPUTE for final and binding arbitration pursuant to
ENDISPUTE's Arbitration Rules incorporated herein by reference, which
arbitration shall take place in Los Angeles, California and shall be the
exclusive remedy of the Parties hereto. The resulting arbitration shall be
deemed a final order of a court having jurisdiction over the subject matter,
shall not be appealable, and shall be enforceable in any court of competent
jurisdiction. Submission to arbitration shall not preclude the right of any
party hereto involved in a dispute regarding this Agreement (each a "Disputing
Party" and collectively, the "Disputing Parties") to institute proceedings at
law or in equity for injunctive or other relief pending the arbitration of a
matter subject to arbitration pursuant to this Agreement. Any documentation and
information submitted by any party in the


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arbitration proceeding shall be kept strictly confidential by the Parties and
the arbitrator.

          In addition to any other relief or award granted by the arbitrator to
either Disputing Party, the arbitrator shall determine the extent to which each
Disputing Party has prevailed as to the material issues raised in the
arbitration, and, based upon such determination, shall apportion to each
Disputing Party its ratable share of (i) the Disputing Parties' reasonable
attorneys' fees and other costs reasonably incurred in the arbitration, (ii) the
expense of the arbitrator, and (iii) all other expenses of the arbitration. The
arbitrator shall make such determination and apportionment whether or not the
dispute proceeds to a final award.

          6.8. SEVERABILITY. Should a court or other body of competent
jurisdiction determine that any provision of this Agreement is excessive in
scope or otherwise invalid or unenforceable, such provision shall be adjusted
rather than voided, if possible, and all other provisions of this Agreement
shall be deemed valid and enforceable to the extent possible.

          6.9. COUNTERPARTS. This Agreement may be executed in one or more
counterparts, all of which taken together shall constitute one and the same
Agreement.

          6.10 INDEMNIFICATION. In addition to any rights to indemnification to
which Officer is entitled under the Corporation's Articles of Incorporation and
By-Laws, Corporation shall indemnify Officer at all times during and after the
Term of this Agreement to the maximum extent permitted under Section 2-418 of
the General Corporation Law of the State of Maryland or any successor provision
thereof and any other applicable state law, and shall pay Officer's expenses in
defending any civil or criminal action, suit, or proceeding in advance of the
final disposition of such action, suit, or proceeding, to the maximum extent
permitted under such applicable state laws.




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          IN WITNESS WHEREOF, the Parties hereto have executed this Agreement.

                                   CORPORATION:

                                   ALEXANDRIA REAL ESTATE

                                   EQUITIES, INC.

                                   a Maryland corporation

                                   By: /s/ JOEL S. MARCUS
                                       -------------------------------------
                                       Joel S. Marcus
                                       Chief Executive Officer


                                   Date: FEBRUARY 4, 2000
                                         -----------------------------------

                                   OFFICER:

                                   /s/ LAURIE A. ALLEN
                                   ------------------------------------------
                                          Laurie A. Allen


                                   Date: FEBRUARY 4, 2000
                                         ------------------------------------



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