Exhibit 99.1

CommonWealth REIT Announces

2011 Second Quarter Results

Newton, MA (August 3, 2011): CommonWealth REIT (NYSE: CWH) today announced financial results for the quarter and six months ended June 30, 2011.

Results for the Quarter Ended June 30, 2011:

Normalized funds from operations, or Normalized FFO, available for common shareholders for the quarter ended June 30, 2011 was $66.0 million, or $0.92 per share basic and $0.91 per share diluted, compared to Normalized FFO available for common shareholders for the quarter ended June 30, 2010 of $60.2 million, or $0.93 per share basic and $0.92 per share diluted.

Net income (loss) available for common shareholders was $9.5 million for the quarter ended June 30, 2011, compared to ($2.7) million for the same quarter last year.  Net income (loss) available for common shareholders per share, basic and diluted (EPS), for the quarters ended June 30, 2011 and 2010 was $0.13 and ($0.04), respectively.  Net income for the quarter ended June 30, 2010 includes a loss of $21.5 million, or $0.33 per share, on asset impairment, partially offset by a gain of $11.5 million, or $0.18 per share, on sale of properties.

The weighted average number of basic and diluted common shares outstanding was 72,144,400 and 79,442,565, respectively, for the quarter ended June 30, 2011, and 64,595,417 and 71,893,582, respectively, for the quarter ended June 30, 2010.

A reconciliation of net income determined according to U.S. generally accepted accounting principles, or GAAP, to FFO and Normalized FFO for the quarters ended June 30, 2011 and 2010 appears later in this press release.

A Maryland Real Estate Investment Trust with transferable shares of beneficial interest listed on the New York Stock Exchange.  No shareholder, Trustee or officer is personally liable for any act or obligation of the Trust.

Results for the Six Months Ended June 30, 2011:

Normalized FFO available for common shareholders for the six months ended June 30, 2011 was $127.8 million, or $1.77 per share basic and $1.76 per share diluted, compared to Normalized FFO available for common shareholders for the six months ended June 30, 2010 of $120.2 million, or $1.98 per share basic and $1.95 per share diluted.

Net income available for common shareholders was $47.2 million for the six months ended June 30, 2011, compared to $22.0 million for the same quarter last year.  Net income available for common shareholders per share, basic and diluted (EPS), for the six months ended June 30, 2011 and 2010 was $0.65 and $0.36, respectively.  Net income for the six months ended June 30, 2011 includes gains of $34.6 million, or $0.48 per share, from the sale of properties.  Net income for the six months ended June 30, 2010 includes gains of $11.5 million, or $0.19 per share, on the sale of properties, and $16.4 million, or $0.27 per share, on the issuance of shares by an equity investee, partially offset by a loss of $21.5 million, or $0.35 per share, on asset impairment.

The weighted average number of basic and diluted common shares outstanding was 72,141,559 and 79,439,724, respectively, for the six months ended June 30, 2011, and 60,685,295 and 67,983,460, respectively, for the six months ended June 30, 2010.

A reconciliation of net income determined according to GAAP, to FFO and Normalized FFO for the six months ended June 30, 2011 and 2010 appears later in this press release.

Occupancy and Leasing Results (excluding properties classified in discontinued operations):

As of June 30, 2011, 87.5% of CWH’s total square feet was leased, compared to 87.5% as of March 31, 2011 and 88.0% as of June 30, 2010.

CWH signed lease renewals for 712,000 square feet and new leases for 549,000 square feet during the quarter ended June 30, 2011 which had weighted average rental rates that were 2% above prior rents for the same space.  Average lease terms for leases signed during the second quarter of 2011 were 6.2 years.  Commitments for tenant improvement and leasing commission (TI/LC) costs for leases signed during the quarter ended June 30, 2011 totaled $15.71 per square foot on average.

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Recent Investment and Sales Activities:

Since April 1, 2011, CWH has acquired ten properties with approximately 2.0 million square feet for an aggregate purchase price of approximately $302.7 million, including the assumption of $56.3 million of mortgage debt and excluding closing costs, and it has entered agreements to acquire four properties with approximately 2.9 million square feet for an aggregate purchase price of approximately $531.1 million, including the assumption of $265.0 million of mortgage debt and excluding closing costs:

·                  In May 2011, CWH closed on the previously reported acquisition of a central business district, or CBD, office property located in Chicago, IL with 1,070,388 square feet.  This property is 85% leased to 60 tenants for a weighted (by rents) average lease term of 6.6 years.  The purchase price was $162.2 million, excluding closing costs.

·                  In June 2011, CWH closed on the previously reported acquisition of four suburban office properties located in Stafford, VA with a combined 149,023 square feet.  These properties are 100% leased to ten tenants for a weighted (by rents) average lease term of 1.7 years.  The aggregate purchase price was $25.7 million, including the assumption of $15.0 million of mortgage debt and excluding closing costs.

·                  In June 2011, CWH closed on the previously reported acquisition of four suburban office properties located in Folsom, CA with a combined 269,254 square feet.  These properties are 93% leased to nine tenants for a weighted (by rents) average lease term of 3.6 years.  The purchase price was $46.3 million, including the assumption of $41.3 million of mortgage debt and excluding closing costs.

·                  In July 2011, CWH acquired a CBD office property located in Birmingham, AL with 514,893 square feet.  This property is 76% leased to 14 tenants for a weighted (by rents) average lease term of 8.7 years.  The purchase price was $68.5 million, excluding closing costs.

·                  As previously reported in May 2011, CWH entered an agreement to acquire two CBD office properties located in Chicago, IL with a combined 1,571,386 square feet.  These properties are 97% leased to 49 tenants for a weighted (by rents) average lease term of 8.4 years.  The aggregate purchase price is $390.0 million, including the assumption of $265.0 million of mortgage debt and excluding closing costs.  CWH expects to acquire these properties during the third quarter of 2011; however, this acquisition is subject to customary closing conditions, including the assumption of existing mortgage debt, and no assurance can be given that CWH will acquire these properties in that time period or at all.

·                  In July 2011, CWH entered an agreement to acquire a CBD office property located in New Orleans, LA with 1,256,991 square feet.  This property is 88% leased to 61 tenants for a weighted (by rents) average lease term of 5.0 years.  The purchase price is $107.0 million, excluding closing costs.  CWH expects to acquire this property during the third quarter of 2011; however, this acquisition is subject to customary closing conditions and no assurance can be given that CWH will acquire this property in that time period or at all.

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·                  In July 2011, CWH entered an agreement to acquire a CBD office property located in Portland, OR with 106,658 square feet.  This property is 100% leased to one tenant for a lease term of 10.8 years.  The purchase price is $34.1 million, excluding closing costs.  CWH expects to acquire this property during the third quarter of 2011; however, this acquisition is subject to customary closing conditions and no assurance can be given that CWH will acquire this property in that time period or at all.

As previously reported, CWH also currently has 27 properties located throughout the United States with a combined 2.9 million square feet listed for sale; however, no assurance can be given that any of these properties will be sold.

Recent Financing Activities:

In June 2011, CWH issued 11.0 million series E cumulative redeemable preferred shares in a public offering, raising net proceeds of approximately $266 million.  Each series E preferred share has a liquidation preference of $25.00 and requires dividends of $1.8125, or 7 ¼% of the liquidation preference per annum, payable in equal quarterly payments.  Each series E preferred share is redeemable at CWH’s option for $25.00 plus accrued and unpaid dividends at any time on or after May 15, 2016.  CWH used the net proceeds from this offering to reduce amounts outstanding under its revolving credit facility.

In June 2011, CWH repaid at maturity $29.2 million of 7.435% mortgage debt using cash on hand.

In July 2011, CWH issued 11.5 million common shares in a public offering, raising net proceeds of approximately $264 million.  CWH used the net proceeds from this offering to repay amounts outstanding under its revolving credit facility and for general business purposes, including funding acquisitions.

In July 2011, CWH prepaid at par plus a premium $23.2 million of 8.05% mortgage debt due in 2012, using cash on hand and proceeds from its 11.5 million common share offering.

Conference Call:

On August 3, 2011, at 1:00 p.m. Eastern Time, Adam Portnoy, Managing Trustee and President, and John Popeo, Chief Financial Officer, will host a conference call to discuss the second quarter financial results.

The conference call telephone number is (800) 230-1074.  Participants calling from outside the United States and Canada should dial (612) 332-0932.  No pass code is necessary to access either call.  Participants should dial in about 15 minutes prior to the scheduled start of the call.  A replay of the conference call will be available through 11:59 p.m. Eastern Time on Wednesday, August 10th.  To hear the replay, dial (320) 365-3844.  The replay pass code is 179322.

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A live audio webcast of the conference call will also be available in a listen only mode on CWH’s website, which is located at www.cwhreit.com.  Participants wanting to access the webcast should visit CWH’s website about five minutes before the call.  The archived webcast will be available for replay on CWH’s website for about one week after the call.  The recording and retransmission in any way of CWH’s second quarter conference call is strictly prohibited without the prior written consent of CWH.

Supplemental Data:

A copy of CWH’s Second Quarter 2011 Supplemental Operating and Financial Data is available for download at CWH’s website, www.cwhreit.com.

CommonWealth REIT is a real estate investment trust, or REIT, which primarily owns office and industrial properties located throughout the United States.  As of June 30, 2011, CWH owned 499 properties with 67.5 million square feet, including 17.9 million square feet of industrial and commercial lands in Oahu, Hawaii and 11 properties with a combined 1.8 million square feet in Australia.  CWH is headquartered in Newton, MA.

Please see the pages attached hereto for a more detailed statement of our operating results and financial condition and for an explanation of our calculation of FFO and Normalized FFO.  CWH’s website is not incorporated as part of this press release.

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WARNING CONCERNING FORWARD LOOKING STATEMENTS

THIS PRESS RELEASE CONTAINS STATEMENTS WHICH CONSTITUTE FORWARD LOOKING STATEMENTS WITHIN THE MEANING OF THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995 AND OTHER SECURITIES LAWS.  ALSO, WHENEVER CWH USES WORDS SUCH AS “BELIEVE”, “EXPECT”, “ANTICIPATE”, “INTEND”, “PLAN”, “ESTIMATE”, OR SIMILAR EXPRESSIONS, CWH IS MAKING FORWARD LOOKING STATEMENTS.  THESE FORWARD LOOKING STATEMENTS AND THEIR IMPLICATIONS ARE BASED UPON CWH’S PRESENT INTENT, BELIEFS OR EXPECTATIONS, BUT FORWARD LOOKING STATEMENTS AND THEIR IMPLICATIONS ARE NOT GUARANTEED TO OCCUR AND MAY NOT OCCUR. CWH’S ACTUAL RESULTS MAY DIFFER MATERIALLY FROM THOSE CONTAINED IN OR IMPLIED BY CWH’S FORWARD LOOKING STATEMENTS AS A RESULT OF VARIOUS FACTORS. FOR EXAMPLE:

·                  THIS PRESS RELEASE STATES THAT CWH HAS ENTERED INTO AGREEMENTS TO ACQUIRE CERTAIN PROPERTIES.  THESE TRANSACTIONS ARE SUBJECT TO VARIOUS TERMS AND CONDITIONS TYPICAL OF COMMERCIAL REAL ESTATE TRANSACTIONS.  THESE TERMS AND CONDITIONS MAY NOT BE MET.  AS A RESULT, SOME OR ALL OF THESE TRANSACTIONS MAY NOT OCCUR OR MAY BE DELAYED.

·                  THIS PRESS RELEASE STATES THAT CWH IS CURRENTLY MARKETING CERTAIN PROPERTIES FOR SALE.  THERE IS NO GUARANTEE THAT CWH WILL FIND BUYERS FOR THESE PROPERTIES OR THAT THE TERMS OFFERED BY POTENTIAL BUYERS WILL BE ACCEPTABLE.  AS A RESULT, SOME OR ALL OF THESE PROPERTIES MAY NOT BE SOLD.

THE INFORMATION CONTAINED IN CWH’S FILINGS WITH THE SECURITIES AND EXCHANGE COMMISSION, INCLUDING UNDER “RISK FACTORS” IN CWH’S PERIODIC REPORTS, IDENTIFIES OTHER IMPORTANT FACTORS THAT COULD CAUSE CWH’S ACTUAL RESULTS TO DIFFER MATERIALLY FROM THOSE STATED IN OR IMPLIED BY CWH’S FORWARD LOOKING STATEMENTS. CWH’S FILINGS WITH THE SECURITIES AND EXCHANGE COMMISSION ARE AVAILABLE ON ITS WEBSITE AT WWW.SEC.GOV.

YOU SHOULD NOT PLACE UNDUE RELIANCE UPON FORWARD LOOKING STATEMENTS.

EXCEPT AS REQUIRED BY LAW, CWH DOES NOT INTEND TO UPDATE OR CHANGE ANY FORWARD LOOKING STATEMENTS AS A RESULT OF NEW INFORMATION, FUTURE EVENTS OR OTHERWISE.

(END)

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CommonWealth REIT

Consolidated Statements of Income and Normalized Funds from Operations

(amounts in thousands, except per share data)

(unaudited)

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CommonWealth REIT

Consolidated Statements of Income and Normalized Funds from Operations (continued)

(amounts in thousands, except per share data)

(unaudited)

(1)    We calculate FFO and Normalized FFO as shown above.  FFO is calculated on the basis defined by The National Association of Real Estate Investment Trusts, or NAREIT, which is net income, computed in accordance with GAAP, excluding gain or loss on sale of properties, plus real estate depreciation and amortization and FFO from equity investees.  Our calculation of Normalized FFO differs from NAREIT’s definition of FFO because we exclude acquisition related costs as described in Note 2 below, gains from issuance of shares by equity investees, loss on asset impairment, the difference between average minimum rent and interest earned from direct financing lease and the difference between FFO and Normalized FFO from equity investees.  We consider FFO and Normalized FFO to be appropriate measures of performance for a REIT, along with net income and cash flow from operating, investing and financing activities. We believe that FFO and Normalized FFO provide useful information to investors because, by excluding the effects of certain historical amounts, such as depreciation expense, FFO and Normalized FFO can facilitate a comparison of our operating performances between historical periods.  FFO and Normalized FFO are among the factors considered by our Board of Trustees in determining the amount of distributions to shareholders.  FFO and Normalized FFO do not represent cash generated by operating activities in accordance with GAAP and should not be considered an alternative to net income or cash flow from operating activities as a measure of financial performance or liquidity.  Other REITs and real estate companies may calculate FFO and Normalized FFO differently than us.

(2)   Represents costs associated with acquisitions that are expensed pursuant to the Business Combinations Topic of the FASB Accounting Standards CodificationTM.

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CommonWealth REIT

Consolidated Statements of Income and Normalized Funds from Operations (continued)

(amounts in thousands, except per share data)

(unaudited)

(3)   As of June 30, 2011, our 15,180 outstanding series D preferred shares were convertible into 7,298 common shares.  The effect of a conversion of our series D convertible preferred shares on income from continuing operations available for common shareholders per share is anti-dilutive to income, but dilutive to FFO and Normalized FFO for all periods presented, except for FFO for the quarter ended June 30, 2010.  Set forth below is the calculation of diluted net income available for common shareholders, diluted FFO available for common shareholders, diluted Normalized FFO available for common shareholders and diluted weighted average common shares outstanding.

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CommonWealth REIT

Consolidated Balance Sheets

(amounts in thousands, except share data)

(unaudited)

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