First Amendment to Second Amended and Restated Credit Agreement by and among Alexandria Real Estate Equities, Inc., Subsidiaries, Lenders, and Bank of America, N.A.

THIS FIRST AMENDMENT TO SECOND AMENDED AND RESTATED CREDIT AGREEMENT (this "Amendment"), dated as of December 1, 2006, is entered into among Alexandria Real Estate Equities, Inc., a Maryland corporation ("Parent"), Alexandria Real Estate Equities, L.P., a Delaware limited partnership ("Operating Partnership"), ARE-QRS Corp., a Maryland corporation ("QRS"), ARE Acquisitions, LLC, a Delaware limited liability company ("ARE"), and the other borrowers set forth on the signature pages hereto (collectively, together with Parent, Operating Partnership, QRS and ARE, the "Borrowers"), the Lenders identified on the signature pages hereto and Bank of America, N.A., as administrative agent (the "Administrative Agent"). Terms used but not otherwise defined herein shall have the meanings provided in the Credit Agreement described below.

WHEREAS, the Borrowers, the Lenders party thereto, and the Administrative Agent entered into that certain Second Amended and Restated Credit Agreement dated as of October 31, 2006 (the "Existing Credit Agreement");

WHEREAS, the Borrowers have requested that the Required Lenders agree to amend certain provisions of the Credit Agreement as hereinafter set forth; and

WHEREAS, the Required Lenders have agreed to such modifications on the terms and conditions set forth herein.

NOW, THEREFORE, in consideration of the agreements hereinafter set forth, and for other good and valuable consideration, the receipt and adequacy of which are hereby acknowledged, the parties hereto agree as follows:

SUBPART 1.1 Certain Definitions. Unless otherwise defined herein or the context otherwise requires, the following term used in this Amendment, including its preamble and recitals, have the following meanings:

SUBPART 1.2 Other Definitions. Unless otherwise defined herein or the context otherwise requires, terms used in this Amendment, including its preamble and recitals, have the meanings provided in the Existing Credit Agreement.

Effective on (and subject to the occurrence of) the Amendment No. 1 Effective Date, the Existing Credit Agreement is hereby amended in accordance with this Part 2.

SUBPART 2.1 Amendment to Section 2.15(a). Clause (iv) contained in Section 2.15(a) of the Existing Credit Agreement is hereby amended and restated to read as follows:

SUBPART 2.2 Amendment to Section 2.15(b). Clause (iv) contained in Section 2.15(b) of the Existing Credit Agreement is hereby amended and restated to read as follows:

SUBPART 3.1 Amendment No. 1 Effective Date. This Amendment shall be and become effective as of the date hereof (the "Amendment No. 1 Effective Date") when all of the conditions set forth in this Part 3 shall have been satisfied, and thereafter this Amendment shall be known, and may be referred to, as the "Amendment".

SUBPART 3.2 Execution of Counterparts of Amendment. The Administrative Agent shall have received counterparts of this Amendment, which collectively shall have been duly executed on behalf of each of the Borrowers, the Required Lenders and the Administrative Agent.

SUBPART 3.3 Fees and Expenses. The Administrative Agent shall have received all out-of-pocket costs and expenses of the Administrative Agent in connection with the preparation, execution and delivery of this Amendment (including without limitation the fees and expenses of Moore & Van Allen PLLC, special counsel to the Administrative Agent to the extent the Borrowers have received an invoice prior to the Amendment No. 1 Effective Date).

SUBPART 4.1 Representations and Warranties. The Borrowers hereby represent and warrant to the Administrative Agent and the Lenders that, after giving effect to this Amendment, (a) no Default or Event of Default exists under the Existing Credit Agreement and (b) the representations and warranties set forth in Article V of the Existing Credit Agreement are true and correct in all material respects on and as of the date hereof, subject to the limitations set forth therein, as if made on and as of such date (except to the extent such representations and warranties expressly relate to another date in which case such representations and warranties shall be true and correct in all material respects as of such date).

SUBPART 4.2 Ratification of Credit Documents.

SUBPART 4.3 Authority/Enforceability.

SUBPART 4.4 Cross-References. References in this Amendment to any Part or Subpart are, unless otherwise specified, to such Part or Subpart of this Amendment.

SUBPART 4.5 Counterparts/Telecopy. This Amendment may be executed by the parties hereto in several counterparts, each of which shall be deemed to be an original and all of which shall constitute together but one and the same agreement. Delivery of executed counterparts of the Amendment by telecopy or other electronic means shall be effective as an original and shall constitute a representation that an original shall be delivered.

SUBPART 4.6 Governing Law. THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

SUBPART 4.7 Successors and Assigns. This Amendment shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns.

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IN WITNESS WHEREOF, the parties hereto have executed this Amendment to the Credit Agreement as of the date first above written.

BORROWERS:

ADMINISTRATIVE AGENT:

LENDERS: