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

     "Asset Value" means, as of any date of determination and without double counting any item, the sum of the following:

     (a) with respect to any improved Real Property (other than Real Property constituting Development Investments) owned by a Person for a full four consecutive fiscal quarter period or longer, an amount equal to (i) the Adjusted NOI of such Person from such Real Property for the prior four full consecutive fiscal quarters divided by (ii) the Capitalization Rate;

     (b) with respect to any Real Property owned by a Person for less than four full consecutive fiscal quarters, an amount equal to (i) the Adjusted NOI of such Real Property for the period which a Person has owned and operated such Real Property, adjusted by the Borrowers to an annual Adjusted NOI in a manner reasonably acceptable to the Administrative Agent, divided by (ii) the Capitalization Rate;

     (c) with respect to improved Real Property that is not a Development Investment but which is being renovated by a Person or with respect to which a partial or total renovation was recently completed by a Person, an amount as determined at the sole election of the Administrative Agent based on (i) the annualized Adjusted NOI with respect to such Real Property, annualized based on bona fide, arms length signed tenant leases which are in full force and effect requiring current rental payments, and divided by the Capitalization Rate, or (ii) on the cost basis of the Real Property determined in accordance with GAAP; and

     (d) with respect to any Real Property that is Qualified Land, an amount equal to, at the option of the Borrowers, cost basis or the Appraised Value (if any) of such Qualified Land.

     "Borrowing Base" means, as of any date of determination and without duplication, an amount equal to the lesser of (a) the amount which, when added to the total outstanding principal amount of all unsecured Indebtedness of the Parent and its Subsidiaries (including the Outstanding Amount of the Loans), would not exceed the sum of: (i) 60% of the aggregate Asset Value of the Revenue-Producing Properties in the Unencumbered Asset Pool, as of such date, plus (ii) 50% of the aggregate Asset Value of the Qualified Lands in the Unencumbered Asset Pool, as of such date, and (b) the amount which, when added to the total outstanding principal amount of all unsecured Indebtedness of the Parent and its Subsidiaries (including the Outstanding Amount of the Loans), would not cause the Interest Coverage Ratio to be less than 2.00:1.00.

     "Capitalization Rate" means 8.75%.

     "Development Investments" means, as of any date of determination, direct or indirect investments in Real Property which, as of such date, is the subject of ground-up development, new construction, substantial renovation or expansion of improvements to Real Property for its own account, of properties to be used principally for office, office/laboratory, research or manufacturing/warehouse purposes; provided, that, such Real Property or any portion thereof will only constitute a Development Investment from the date construction has commenced thereon until the date on which the Real Property and applicable improvements receive a final certificate of occupancy or equivalent certification allowing legal occupancy for its intended purpose.

     "Fee Letter" means that certain letter agreement dated as of November __, 2005 among the Parent, the Administrative Agent and BAS, which letter agreement supercedes and replaces that certain letter agreement dated as of December 22, 2004 among the Parent, the Administrative Agent and BAS.

     "Leverage Ratio" means, as of the last day of each fiscal quarter, the ratio (expressed as a percentage) of (a) Total Indebtedness of Parent and its Subsidiaries as of that date to (b) the Adjusted Tangible Assets of Parent and its Subsidiaries as of that date.

     "Qualified Unencumbered Asset Pool Property" means Qualified Land and Qualified Revenue-Producing Property.

     "Term Loan Amount" means, at any time, the aggregate principal amount of the Term Loans outstanding, which amount on the Second Amendment Date is equal to $500,000,000, as such amount may be increased from time to time pursuant to Section 2.15 or decreased from time to time.

     "Unencumbered" means, with respect to any Revenue-Producing Property or Qualified Land, that such Revenue-Producing Property or Qualified Land (a) is not subject to any Lien other than Liens permitted under Section 7.01, (b) is not subject to any Negative Pledge and (c) is not held by a Person any of whose direct or indirect equity interests are subject to a Lien or Negative Pledge.

     "Unencumbered Asset Pool" means, as of any date of determination, (a) the Initial Pool Properties, plus (b) each other Qualified Unencumbered Asset Pool Property added to the Unencumbered Asset Pool pursuant to Section 2.16 as of such date, excluding (c) any Revenue-Producing Property or Qualified Land removed from the Unencumbered Asset Pool pursuant to Section 2.16 as of such date.

     "Appraised Value" means, as of any date of determination, without duplication, with respect to any Real Property, the appraised value (if any) thereof based on its unimproved as-is basis determined pursuant to an appraisal prepared by an M.A.I. certified appraisal and otherwise reasonably satisfactory to Administrative Agent (it being understood and agreed that in no event shall the Borrowers be required to deliver updated appraisals more frequently than once during any 24-month period).

     "Minimum Book Value" means, as of any date of determination, without duplication, the sum of: (a) all consolidated assets of Parent and its Subsidiaries as of that date, plus (b) Parent's and its Subsidiaries' minority interest in unconsolidated assets as of that date, minus (i) Intangible Assets of Parent and its Subsidiaries and (ii) Total Liabilities of Parent and its Subsidiaries as of that date.

     "Qualified Land" means, as of any date of determination, without duplication, Real Property that:

     (a) has received all entitlements required for the contemplated development of the Real Property into Revenue-Producing Property;

     (b) is wholly owned in fee simple absolute by Parent or any other Borrower that is a Wholly-Owned Subsidiary;

     (c) to the best of Borrowers' knowledge and belief, does not have any title, survey, environmental or other defects that would give rise to a materially adverse effect as to the value, use of or ability to sell or refinance such property;

     (d) is Unencumbered; and

     (e) would not cause the Borrowers to be in violation of the covenant set forth in Section 6.13.

     "Qualified Revenue-Producing Property" means Revenue-Producing Property that:

     (a) is wholly owned in fee simple absolute or a leasehold interest pursuant to a Mortgageable Ground Lease by Parent or any other Borrower that is a Wholly-Owned Subsidiary;

     (b) is occupied or available for occupancy (subject to final tenant improvements);

     (c) to the best of Borrowers' knowledge and belief, does not have any title, survey, environmental or other defects that would give rise to a materially adverse effect as to the value, use of or ability to sell or refinance such property;

     (d) is Unencumbered; and

     (e) would not cause the Borrowers to be in violation of the covenant set forth in Section 6.13.

     "Second Amendment Date" means November __, 2005. "Total Indebtedness" means, as to any Person at a particular time, without duplication, all of the following, whether or not included as indebtedness or liabilities in accordance with GAAP:

     (a) all obligations of such Person for borrowed money and all obligations of such Person evidenced by bonds, debentures, notes, loan agreements or other similar instruments;

     (b) all direct or contingent obligations of such Person arising under letters of credit (including standby and commercial), bankers' acceptances and bank guaranties;

     (c) net obligations of such Person under any Swap Contract;

     (d) all obligations of such Person to pay the deferred purchase price of property or services (other than trade accounts payable in the ordinary course of business);

     (e) indebtedness (excluding prepaid interest thereon) secured by a Lien on property owned or being purchased by such Person (including indebtedness arising under conditional sales or other title retention agreements), whether or not such indebtedness shall have been assumed by such Person or is limited in recourse;

     (f) Capital Lease Obligations; and

     (g) all Guarantees of such Person in respect of any of the foregoing.

     For all purposes hereof, Total Indebtedness shall not include any Minority Interest's share of any of the foregoing. The amount of any net obligation under any Swap Contract on any date shall be deemed to be (i) for any date on or after the date such Swap Contracts have been closed out and termination value(s) determined in accordance therewith, such termination value(s), and (ii) for any date prior to the date referenced in clause (i), zero. The amount of any Capital Lease Obligation as of any date shall be deemed to be the amount of Attributable Indebtedness in respect thereof as of such date.

     (b) Term Loan. Subject to the terms and conditions set forth herein, each Term Lender severally agrees to fund the portion of the Term Loan Amount represented by its Term Loan Commitment to the Borrowers on the Closing Date or Second Amendment Date, as applicable, in an aggregate amount not to exceed such Term Lender's Term Loan Commitment or the Term Loan Amount. The Term Loan shall be made in two draws on the Closing Date and the Second Amendment Date. To the extent all or any portion of the Term Loans are repaid or prepaid, they may not be reborrowed. Term Loans may be Base Rate Loans or Eurodollar Rate Loans, as further provided herein.

     (a) Request for Increase. Provided there exists no Default or Event of Default (nor would any occur after giving effect to the increase described herein) and in consultation with the Administrative Agent in order to minimize costs associated therewith, upon notice to the Administrative Agent (which shall promptly notify the Lenders), the Borrowers may request an increase in the Aggregate Commitments (which may be, at the option of the Borrowers, Revolving Commitments and/or Term Loan Commitments) by an aggregate amount not exceeding $200,000,000; provided, that, any such request for an increase shall be in a minimum amount of $25,000,000 (unless approved by the Administrative Agent). At the time of sending such notice, the Borrowers (in consultation with the Administrative Agent) shall specify the time period within which each Lender is requested to respond (which shall in no event be less than ten Business Days from the date of delivery of such notice to the Lenders).

     2.16 Unencumbered Asset Pool. Borrowers may at any time add a Qualified Unencumbered Asset Pool Property to the Unencumbered Asset Pool pursuant to this Section 2.16, by Borrowers' delivery to the Administrative Agent (which the Administrative Agent shall promptly distribute to the Revolving Lenders) of the following:

     (a) a complete description of the proposed Qualified Unencumbered Asset Pool Property;

     (b) for any Revenue-Producing Property only, the prior twelve (12) months' operating income statements related to such Qualified Unencumbered Asset Pool Property (to the extent available);

     (c) for any Revenue-Producing Property only, cash flow projections for such Qualified Unencumbered Asset Pool Property for at least the next twelve (12) months;

     (d) for any Revenue-Producing Property only, a description of all tenants and leases with respect to such Qualified Unencumbered Asset Pool Property;

     (e) a certification of a Responsible Officer of the Borrowers that Parent has obtained a current written report prepared by a qualified independent expert with respect to Hazardous Materials related thereto which discloses that such property would not be in violation of the representations and covenants of this Agreement; and

     (f) such other written materials reasonably requested by any Revolving Lender.

     Borrowers may remove any Qualified Unencumbered Asset Pool Property from the Unencumbered Asset Pool by delivery to the Administrative Agent (for prompt distribution to the Revolving Lenders) of a written notice to that effect, accompanied by a certificate of a Responsible Officer of Borrowers setting forth the revised Borrowing Base as of the most recently-ended fiscal quarter for which financial statements are required to be delivered pursuant to this Agreement resulting from such removal, which removal shall be effective on the third (3rd) day after receipt of such notice by Administrative Agent.

     (a) is duly organized or formed, validly existing and in good standing under the Laws of the jurisdiction of its incorporation or organization except to the extent permitted by Sections 7.04, or 10.21.

     (c) As soon as practicable, and in any event within 60 days after the end of each of the first 3 fiscal quarters in any fiscal year, statements of operating income for such fiscal quarter for each of the Revenue-Producing Properties in the Unencumbered Asset Pool and a summary Rent Roll for each of the Revenue-Producing Properties in the Unencumbered Asset Pool, each in reasonable detail. For the fourth fiscal quarter of each fiscal year, as soon as practicable, and in any event within 90 days after the end of such fourth fiscal quarter, provide such above-mentioned detail; and

     (a) As soon as practicable, and in any event no later than 90 days after the commencement of each fiscal year, a budget and projection by fiscal quarter for that fiscal year and by fiscal year for the next two succeeding fiscal years, including for the first such fiscal year, projected consolidated balance sheets, statements of operations and statements of cash flow and, for the second and third such fiscal years, projected consolidated balance sheets and statements of operations and cash flows, of Parent and its Subsidiaries, all in reasonable detail;

     (g) Not later than sixty (60) days after the end of each fiscal quarter of the Borrowers (other than the fourth fiscal quarter in any fiscal year), (i) a statement listing the properties of Parent and its respective Subsidiaries which are Development Investments and providing a brief summary of the status of such development, and (ii) an updated Schedule 5.13 containing a current listing of all then existing Subsidiaries. Not later than ninety (90) days after the fourth fiscal quarter in any fiscal year, the items required to be delivered in clause (i) and (ii) above for such fourth fiscal quarter;

     (a) Cause each of the Revenue-Producing Properties in the Unencumbered Asset Pool to satisfy all of the following conditions:

     (b) Cause no more than 25% of the total Borrowing Base to be derived from Qualified Lands.

     (c) Provide to the Administrative Agent on and as of the Second Amendment Date as part of the Compliance Certificate (i) a list of the Revenue-Producing Properties and Qualified Lands in the Unencumbered Asset Pool, (ii) the certification of a Responsible Officer of the Borrowers of the Asset Values of such properties and that such properties are in compliance with Section 6.13 (together with appraisals (if any) to support any applicable Appraised Values for each Qualified Land), (iii) operating statements setting forth the NOI for each of the Revenue-Producing Properties in the Unencumbered Asset Pool for the previous four fiscal quarters (or such shorter period as the Revenue-Producing Property has been held by the Borrowers if such statements are not available to Borrowers) certified as true and correct by a Responsible Officer of the Borrowers, and (iv) a certificate that the Revenue-Producing Properties and Qualified Lands in the Unencumbered Asset Pool comply with the terms of Sections 5.09 and 5.19. If all or any material portion of a Revenue-Producing Property or a Qualified Land within the Unencumbered Asset Pool shall be materially damaged or taken by condemnation, then such property shall no longer be a part of the Unencumbered Asset Pool unless and until such damage is repaired or restored, such property becomes fully operational and the Administrative Agent shall receive evidence satisfactory to the Administrative Agent of the value and NOI of such Revenue-Producing Property or the Appraised Value of Qualified Land following such repair or restoration.

     6.14 Revenue-Producing Property and Qualified Land. Cause each Revenue-Producing Property and each Qualified Land in the Unencumbered Asset Pool to remain a Qualified Unencumbered Asset Pool Property so long as it is in the Unencumbered Asset Pool; provided, that, nothing herein shall preclude the removal of any such property from the Unencumbered Asset Pool in accordance with this Agreement.

     6.15 Additional Borrowers. Cause each Wholly-Owned Subsidiary of Parent which is not then a Borrower and which holds a Revenue-Producing Property or Qualified Land which becomes part of the Unencumbered Asset Pool, to execute and deliver a joinder agreement concurrently with the addition of such Revenue-Producing Property or such Qualified Land to the Unencumbered Asset Pool.

     (f) Investments in Real Property of the Borrower and their Subsidiaries consisting of (i) Development Investments (the amount of such Investment shall be an amount equal to the aggregate costs incurred in connection therewith), (ii) undeveloped land without improvements, or (iii) any other Real Property, other than an improved real estate property used principally for office, office/laboratory, research, or manufacturing/warehouse purposes (and appurtenant amenities); provided, that, as of the most recently ended fiscal quarter, the book value of such Investments may not exceed 35% of the Adjusted Tangible Assets. To determine such book value of Investments described in this Section 7.02(f) which are not owned 100%, directly or indirectly, by Parent or any of its Subsidiaries, the book value of such Investment shall be adjusted by multiplying the same by the Parent's or such Subsidiaries' interest therein during the fiscal quarter of the Parent ending as of the date of determination of such book value;

     (g) Investments in Development Investments; provided, that, at any time the aggregate amount of costs incurred in connection therewith from the date of computation of acquiring the applicable Real Property and developing, constructing, renovating, rehabilitating and leasing the improvements thereon, to any date of determination, does not exceed 25% of the Adjusted Tangible Assets as of the most recently ended fiscal quarter;

     7.09 Burdensome Agreements. Enter into any agreement, instrument or transaction which has or may have the effect of prohibiting or limiting any Borrower's ability to pledge to Administrative Agent the Revenue-Producing Property and Qualified Land within the Unencumbered Asset Pool. Borrowers and their respective Subsidiaries, shall take such actions as are necessary to preserve the right and ability of Borrowers to pledge to Administrative Agent for the benefit of Lenders those Revenue-Producing Properties and Qualified Lands without any such pledge after the date hereof causing or permitting the acceleration (after the giving of notice or the passage of time, or otherwise) of any other Indebtedness of Borrowers or any of their respective Subsidiaries. Borrowers shall, upon demand, provide to the Administrative Agent such evidence as the Administrative Agent may reasonably require to evidence compliance with this Section 7.09, which evidence shall include, without limitation, copies of any agreements or instruments which would in any way restrict or limit a Borrower's ability to pledge to Administrative Agent Revenue- Producing Properties and Qualified Lands within the Unencumbered Asset Pool as security for the Obligations, or which provide for the occurrence of a default (after the giving of notice or the passage of time, or otherwise) if Revenue- Producing Properties or Qualified Lands within the Unencumbered Asset Pool are pledged to Administrative Agent in the future as security for the Obligations.

     (a) Permit the Fixed Charge Coverage Ratio, as of the last day of any fiscal quarter, to be less than 1.50:1.00;

     (b) Permit the Secured Debt Ratio, as of the last day of any fiscal quarter, to exceed 0.45:1.00;

     (c) Permit the Leverage Ratio, as of the last day of any fiscal quarter, to exceed 0.60:1.00;

     (d) Permit Minimum Book Value, as of the last day of any fiscal quarter, to be less than the sum of (i) $456,000,000, plus (ii) 85% of the net issuance proceeds of all Equity Offerings from and after the Closing Date (excluding the amount of Exchange Proceeds); and

     (e) Permit recourse Indebtedness (whether secured or unsecured) of Parent and its Subsidiaries (excluding the Obligations) to exceed an amount equal to 40% of Adjusted Tangible Assets as of the most recently ended fiscal quarter.

     10.21 Release of Borrower. Notwithstanding anything to the contrary contained in this Agreement, Parent may sell, assign, transfer or dispose of its interest in another Borrower (other than Operating Partnership) that is a Subsidiary of Parent; provided, that, on or before the closing of such sale the Borrowers shall have delivered to the Administrative Agent a certification, together with such other evidence as Administrative Agent may require, that the Borrowers will be in compliance with all covenants in this Agreement after giving effect to such sale, assignment, transfer or other disposition; and, provided, further, that from and after any such sale, the assets of such Borrower shall no longer be included within the Unencumbered Asset Pool. Administrative Agent shall promptly notify the Lenders of any such sale, assignment, transfer or other disposition permitted hereunder. In the event that the Borrowers shall comply with the foregoing provisions, such Borrower shall be released from liability under this Agreement by the Administrative Agent. The Administrative Agent may also release a Borrower from liability if all of the Revenue-Producing Properties and Qualified Lands of such Borrower are sold or all of the Revenue- Producing Properties and Qualified Lands of such Borrower cease to be Unencumbered; provided, that, on or before the effective date of such release, the Borrowers shall have delivered to the Administrative Agent a certification, together with such other evidence as the Administrative Agent may require, that the Borrowers will be in compliance with all covenants in this Agreement after giving effect to such release.