UNDERWRITING AGREEMENT

September 20, 2005

A.G. EDWARDS & SONS, INC.

One North Jefferson Avenue
St. Louis, Missouri 63103

Ladies and Gentlemen:

Alexandria Real Estate Equities, Inc., a Maryland corporation (the “Company”), proposes to issue and sell to A.G. Edwards & Sons, Inc. (the “Underwriter”) an aggregate of 1,200,000 shares (the “Firm Shares”) of common stock, par value $0.01 per share (the “Common Stock”), of the Company.  In addition, solely for the purpose of covering over-allotments, the Company proposes to grant to the Underwriter the option to purchase from the Company up to an additional 180,000 shares of Common Stock (the “Additional Shares”).  The Firm Shares and the Additional Shares are hereinafter collectively sometimes referred to as the “Shares.”  The Shares are described in the Prospectus which is referred to below.

The Company has filed, in accordance with the provisions of the Securities Act of 1933, as amended, and the rules and regulations thereunder (collectively, the “Securities Act”), with the Securities and Exchange Commission (the “Commission”) a Registration Statement (as defined below), including a prospectus which incorporates by reference documents which the Company has filed, or will file, in accordance with the provisions of the Securities Exchange Act of 1934, as amended, and the rules and regulations thereunder (collectively, the “Exchange Act”).  The Company has prepared a prospectus supplement (the “Prospectus Supplement”) to the prospectus included as part of the Registration Statement setting forth the terms of the offering, sale and plan of distribution of the Shares and additional information concerning the Company and its business.   Except where the context otherwise requires, the registration statement filed on Form S-3 (File No. 333-118082), when it became effective, including all documents filed as part thereof or incorporated by reference therein, and including any information contained in the Prospectus (as defined below) subsequently filed with the Commission pursuant to Rule 424(b) under the Securities Act and also including any other registration statement filed pursuant to Rule 462(b) under the Securities Act, is herein called the “Registration Statement,” and the prospectus, including all documents incorporated therein by reference, included in the Registration Statement, as supplemented by the Prospectus Supplement, in the form filed by the Company with the Commission pursuant to Rule 424(b) under the Securities Act on or before the second Business Day (as defined below) following the date of this Underwriting Agreement (the “Agreement”), is herein called the “Prospectus.”  Any reference herein to the Registration Statement, the Prospectus or any amendment or supplement

thereto shall be deemed to refer to and include the documents incorporated by reference therein, and any reference herein to the terms “amend,” “amendment” or “supplement” with respect to the Registration Statement or the Prospectus shall be deemed to refer to and include the filing after the execution hereof of any document with the Commission deemed to be incorporated by reference therein.  For purposes of this Agreement, all references to the Registration Statement, the Prospectus or any amendment or supplement thereto shall be deemed to include any copy filed with the Commission pursuant to its Electronic Data Gathering Analysis and Retrieval System (“EDGAR”), and such copy, as the case may be, shall be identical in content to any Prospectus delivered to the Underwriter for use in connection with the offering of the Shares.

The Company and the Underwriter agree as follows:

1.             Sale and Purchase .  Upon the basis of the warranties and representations and subject to the terms and conditions herein set forth, the Company agrees to issue and sell the Firm Shares to the Underwriter, and the Underwriter agrees to purchase from the Company the Firm Shares at a purchase price of $81.00 per Share.  The Company is advised by the Underwriter that the Underwriter intends (i) to make a public offering of the Firm Shares as soon as the Underwriter deems advisable after this Agreement has been executed and delivered and (ii) initially to offer the Firm Shares upon the terms set forth in the Prospectus.  The Underwriter may from time to time increase or decrease the public offering price after the initial public offering of the Shares to such extent as it may determine.

In addition, the Company hereby grants to the Underwriter the option to purchase, and upon the basis of the warranties and representations and subject to the terms and conditions herein set forth, the Underwriter shall have the right to purchase from the Company all or such portion of the Additional Shares as may be necessary to cover over-allotments made in connection with the offering of the Firm Shares, at the same purchase price per share to be paid by the Underwriter to the Company for the Firm Shares.  This option may be exercised by the Underwriter at any time (but not more than once) on or before the thirtieth day following the date hereof, by written notice to the Company.  Such notice shall set forth the aggregate number of Additional Shares as to which the option is being exercised and the date and time when the Additional Shares are to be delivered (such date and time being herein referred to as the “additional time of purchase”); provided , however , that the additional time of purchase shall not be (i) earlier than the time of purchase (as defined below) or (ii) unless otherwise agreed to by the Company and the Underwriter, earlier than the second or later than the tenth Business Day after the date on which the option shall have been exercised.  As used herein “Business Day” shall mean a day on which the New York Stock Exchange (“NYSE”) is open for trading or commercial banks in the City of New York are open for business.

2.             Payment and Delivery of Firm Shares .  Delivery of the certificates for the Firm Shares to the Underwriter through the facilities of the Depository Trust Company (“DTC”) for the account of the Underwriter shall be made against payment of the purchase price for the Firm Shares by or on behalf of the Underwriter to the Company by federal funds wire transfer.  Such payment and delivery shall be made at 10:00 A.M., New York City time, on September 23, 2005 (unless another time shall be agreed to by the Underwriter and the Company).  The time at which such payment and delivery of the Firm Shares are actually made is herein called the “time of purchase.”  Certificates for the Firm Shares shall be delivered to the Underwriter, through the facilities of DTC, in book-entry form in such names and in such denominations as the Underwriter shall specify no later than the second Business Day preceding the time of purchase.  For the purpose of expediting the checking of the certificates for the Firm Shares by the Underwriter, the Company agrees to make such certificates available to the Underwriter for such purpose at DTC or its designated custodian at least one full Business Day preceding the time of purchase.

3.             Payment and Delivery of Additional Shares .  Payment of the purchase price for the Additional Shares shall be made at the additional time of purchase.  Certificates for the Additional Shares shall be delivered to the Underwriter, through the facilities of DTC, in book-entry form in such names and in such denominations as the Underwriter shall specify no later than the second Business Day preceding the additional time of purchase.  For the purpose of expediting the checking of the certificates for the Additional Shares by the Underwriter, the Company agrees to make such certificates available to the

Underwriter for such purpose at DTC or its designated custodian at least one full Business Day preceding the additional time of purchase.

4.             Representations and Warranties .  The Company and the Underwriter agree as follows:

(a)           The Registration Statement has been filed with the Commission; the Registration Statement and any post-effective amendment thereto, each in the form heretofore delivered to the Underwriter, excluding exhibits thereto but including all documents incorporated by reference in the Prospectus, have been declared effective by the Commission in such form; other than (i) the Registration Statement, (ii) certain prospectus supplements relating to prior offerings of securities sold pursuant to the Registration Statement which have been filed with the Commission pursuant to Rule 424(b) of the Securities Act, and (iii) the Company’s periodic and current reports, no other document with respect to the Registration Statement or any document incorporated by reference therein has heretofore been filed with the Commission; and no stop order suspending the effectiveness of the Registration Statement has been issued and no proceeding for that purpose has been initiated or, to the Company’s knowledge, threatened by the Commission;

(b)           The documents incorporated by reference into the Prospectus, when they became effective or were filed with the Commission, as the case may be, conformed in all material respects to the requirements of the Securities Act or the Exchange Act, as applicable, and none of such documents contained an untrue statement of a material fact or omitted to state a material fact required to be stated therein or necessary to make the statements therein not misleading; and any further documents so filed and incorporated by reference into the Prospectus or any further amendment or supplement thereto, when such documents become effective or are filed with the Commission, as the case may be, will conform in all material respects to the requirements of the Securities Act or the Exchange Act, as applicable, and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information concerning the Underwriter furnished in writing to the Company by the Underwriter expressly for use therein;

(c)           The Registration Statement, at the time it became effective, conformed, and any further amendments or supplements to the Registration Statement, when they become effective, will conform, in all material respects to the requirements of the Securities Act and did not and will not, as of the applicable effective date, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information concerning the Underwriter furnished in writing to the Company by the Underwriter expressly for use therein;

(d)           The Prospectus, when filed with the Commission and at the time of purchase and, if applicable, at the additional time of purchase, conformed or will conform, and any amendment or supplement thereto, at the respective times of filing with the Commission, will conform, in all material respects to the requirements of the Securities Act, and will not, as of such respective filing times, contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information concerning the Underwriter furnished in writing to the Company by the Underwriter expressly for use therein; and the Prospectus Supplement has been or will be so prepared and will be filed pursuant to Rule 424(b) of the Securities Act on or before the second Business Day following the date of this Agreement.

(e)           Neither the Company nor any of its subsidiaries has sustained since the date of the latest audited financial statements included or incorporated by reference in the Prospectus any loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Prospectus, that singly or in the aggregate could be reasonably expected to have a material adverse effect, in or affecting the general affairs, management, financial position, stockholders’ equity or results of operations of the Company and its subsidiaries, taken as a whole (a “Material Adverse Effect”); and, since the respective dates as of which information is given in the Registration Statement and the Prospectus, there has not been any change in the capital stock or long-term debt of the Company or any subsidiary of the Company that constitutes a “significant subsidiary” as defined in Rule 1-02 of Regulation S-X (each such significant subsidiary, a “Subsidiary”), or any Material Adverse Effect or any development involving a Material Adverse Effect, in any such case, otherwise than as set forth or contemplated in the Prospectus;

(f)            The Company and its subsidiaries have good and marketable title in fee simple to all real property (other than (i) the Company’s ground leasehold interest in the 3165 Porter Drive, 2425 Garcia Avenue, 2400 and 2450 Bayshore Parkway, Buildings 79 and 96 Charlestown Navy Yard, 8000, 9000 and 10,000 Virginia Manor Road and 2625, 2627 and 2631 Hanover Street properties, 108 Alexander Road, 9220 Medical Center Drive and (ii) the Company’s interest in the 1311, 1401 and 1431 Harbor Bay Parkway property, in which the Company owns a commercial condominium interest together with an undivided interest in the common areas of the project in which the property is a part) and good and marketable title to all personal property owned by them, in each case free and clear of all liens, encumbrances and defects, except for the related mortgage indebtedness described in the Prospectus and such other liens, encumbrances and defects as are described in the Prospectus or such as could not reasonably be expected to have a Material Adverse Effect and do not materially interfere with the use made and proposed to be made of such property by the Company and its subsidiaries; and any real property and buildings held under lease (other than ground leases referred to above) by the Company and its subsidiaries that are described in the Prospectus are held by them under valid, subsisting and enforceable leases with such exceptions as are not material and do not materially interfere with the use made and proposed to be made of such property and buildings by the Company and its subsidiaries;

(g)           The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Maryland, with power and authority (corporate and other) to own its properties and other assets and conduct its business as described in the Prospectus, and has been duly qualified as a foreign corporation for the transaction of business and is in good standing under the laws of each other jurisdiction in which it owns or leases properties or conducts any business so as to require such qualification, or is subject to no material liability or disability by reason of the failure to be so qualified in any such jurisdiction; each subsidiary of the Company has been duly organized and is validly existing and in good standing under the laws of its jurisdiction of organization; each Subsidiary and its jurisdiction of organization is set forth on Schedule 1(g) hereto; each of the Company’s subsidiaries has power and authority (corporate and other) to own its properties and other assets and conduct its business as described in the Prospectus, and has been duly qualified as a foreign corporation, partnership, limited liability company or other entity, as the case may be, for the transaction of business and is in good standing under the laws of each other jurisdiction in which it owns or leases properties or conducts any business so as to require such qualification, or is subject to no material liability or disability by reason of the failure to be so qualified in any such jurisdiction;

(h)           The Company has an authorized, issued and outstanding capitalization as set forth in the Prospectus, and all of the issued and outstanding shares of stock of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and conform to the description of the stock contained in the Prospectus under the heading “Description of Capital Stock” or in the documents

incorporated by reference into the Prospectus; and all of the issued shares of capital stock, partnership interests or membership interests of each subsidiary of the Company have been duly and validly authorized and issued, are fully paid and non-assessable and (except for directors’ qualifying shares) are owned directly or indirectly by the Company, free and clear of all liens, encumbrances, equities or claims, except such as are described in the Prospectus or such as do not materially interfere with the ownership thereof by the Company and its subsidiaries in each case, except as would not have a Material Adverse Effect;

(i)            The Shares to be issued and sold by the Company to the Underwriter hereunder have been duly and validly authorized and, when issued and delivered against payment therefor as provided herein, will be duly and validly issued and fully paid and non-assessable, will conform to the description of the Common Stock contained in the Prospectus and will not be subject to any preemptive rights of any security holder of the Company; no holder of Shares will be subject to personal liability by reason of being such a holder;  except as set forth in the Prospectus, the issuance, sale or offering of the Shares by the Company will not give rise to any options to purchase, or any preemptive or other rights or warrants to subscribe for, or any obligations or commitments of the Company to issue, sell, convert, exchange or register with the Commission any shares of stock, warrants, convertible securities or obligations of the Company or any shares of stock of or membership interests or partnership interests in any subsidiary or any such warrants, convertible securities or obligations;

(j)            The issue and sale of the Shares by the Company and the compliance by the Company with all of the provisions of this Agreement and the consummation of the transactions herein contemplated will not (i) conflict with or result in a breach or violation of any of the terms or provisions of, or constitute a default under, any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject, except for such conflicts, breaches, violations or defaults that could not be reasonably expected to result in a Material Adverse Effect, (ii) result in any violation of the provisions of the charter or bylaws of the Company or (iii) result in any violation of any statute or any order, rule or regulation of any court or governmental agency or body having jurisdiction over the Company or any of its subsidiaries or any of their properties, except for such violations that could not be reasonably expected to result in a Material Adverse Effect; and no consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Shares or the consummation by the Company of the transactions contemplated by this Agreement, except the registration under the Securities Act of the Shares and such consents, approvals, authorizations, registrations or qualifications (i) as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Shares by the Underwriter, (ii) as may be required pursuant to the listing requirements of the NYSE, (iii) as may be required by the National Association of Securities Dealers, Inc. (“NASD”) or (iv) as have already been obtained;

(k)           Neither the Company nor any of its subsidiaries is (i) in violation of its charter, bylaws or similar organizational document or (ii) in default in the performance or observance of any obligation, agreement, covenant or condition contained in any indenture, mortgage, deed of trust, loan agreement, lease or other agreement or instrument to which it is a party or by which it or any of its properties may be bound, except, in the case of this clause (ii), for such defaults that could not be reasonably expected to result in a Material Adverse Effect;

(l)            Other than as set forth in the Prospectus, there are no legal or governmental proceedings pending to which the Company or any of its subsidiaries is a party or of which any property or other assets of the Company or any of its subsidiaries is the subject which could reasonably be expected to have

a Material Adverse Effect; and, to the best of the Company’s knowledge, no such proceedings are threatened or contemplated by governmental authorities or threatened by others;

(m)          The Company is not and, after giving effect to the offering and sale of the Shares, will not be required to be registered as, an “investment company”, as such term is defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”);

(n)           Ernst & Young LLP, who have certified certain financial statements of the Company and its subsidiaries and certain properties acquired by the Company and its subsidiaries, are independent public accountants as required by the Securities Act;

(o)           The Company and its subsidiaries have filed all federal, state, local and foreign income tax returns which have been required to be filed (except in any case in which the failure to so file would not result in a Material Adverse Effect) and have paid all taxes required to be paid and any other assessment, fine or penalty levied against them, to the extent that any of the foregoing would otherwise be delinquent, except, in all cases, for any such tax, assessment, fine or penalty that is being contested in good faith and except in any case in which the failure to so pay would not result in a Material Adverse Effect;

(p)           Commencing with the Company’s taxable year ended December 31, 1996, the Company has been, and upon the sale of the Shares will continue to be, organized and operated in conformity with the requirements for qualification and taxation as a “real estate investment trust” (a “REIT”) under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended (the “Code”); the proposed method of operation of the Company as described in the Prospectus will enable the Company to continue to meet the requirements for qualification and taxation as a REIT under the Code; the Company intends to continue to operate in a manner which would permit it to qualify as a REIT under the Code; and the Company has no present intention of changing its operations or engaging in activities which would cause it to fail to qualify, or make economically undesirable its continued qualification, as a REIT;

(q)           Except as set forth in the Prospectus, the Company has no knowledge of (i) the presence of any hazardous substances, hazardous materials, toxic substances or hazardous or toxic wastes (collectively, “Hazardous Materials”) on any of the properties owned by it in violation of law or in excess of regulatory action levels that could reasonably be expected to have a Material Adverse Effect or (ii) any unlawful spills, releases, discharges or disposal of Hazardous Materials that have occurred or are presently occurring on or from such properties as a result of any construction on or operation and use of such properties, which presence or occurrence could reasonably be expected to have a Material Adverse Effect; and in connection with the construction on or operation and use of the properties owned by the Company, it has no knowledge of any failure to comply with all applicable local, state and federal environmental laws, regulations, agency requirements, ordinances and administrative and judicial orders that could reasonably be expected to have a Material Adverse Effect;

(r)            The consolidated financial statements of the Company, together with the related schedules and notes thereto, set forth or included or incorporated by reference in the Registration Statement and Prospectus fairly present in all material respects the financial condition of the Company and its consolidated subsidiaries as of the dates indicated and the results of operations, changes in financial position, stockholders’ equity and cash flows for the periods therein specified, in conformity with generally accepted accounting principles consistently applied throughout the periods involved (except as otherwise stated therein); the summary and selected financial and statistical data included or incorporated by reference in the Registration Statement and the Prospectus present fairly in all material respects the information shown therein and, to the extent based upon or derived from the financial statements, have been compiled on a basis consistent with the financial statements presented therein; in

addition, to the extent applicable, the pro forma financial statements of the Company, and the related notes thereto, included or incorporated by reference in the Registration Statement and the Prospectus present fairly in all material respects the information shown therein, have been prepared in accordance with the Commission’s rules and guidelines with respect to pro forma financial statements and have been properly compiled on the basis described therein, and the assumptions used in the preparation thereof are reasonable and the adjustments used therein are appropriate to give effect to the transactions and circumstances referred to therein; furthermore, all financial statements required by Rule 3-14 of Regulation S-X (“Rule 3-14”) have been included or incorporated by reference in the Registration Statement and the Prospectus and any such financial statements are in conformity with the requirements of Rule 3-14; and no other financial statements are required to be set forth or to be incorporated by reference in the Registration Statement or the Prospectus under the Securities Act;

(s)           The Company has not relied upon the Underwriter or legal counsel for the Underwriter for any legal, tax or accounting advice in connection with the offering and sale of the Shares, except with respect to the Blue Sky survey prepared by legal counsel for the Underwriter;

(t)            The Company maintains a system of internal accounting controls sufficient to provid