Exhibit 99.1

International Rectifier Announces Fourth Quarter and Full Year 2011 Results

Fourth Quarter Fiscal Year 2011

·                  June quarter revenue $317.2 million, a 6.9% sequential increase

·                  GAAP EPS $0.55 per fully diluted share

Full Year Fiscal 2011

·                  Revenue $1.18 billion vs. $895.3 million, a 31.4% increase year-over-year

·                  Gross margin 39.5% vs. 32.7%, a 6.8% increase year-over-year

·                  GAAP EPS $2.33 vs. $1.13 per fully diluted share, a 106% increase year-over-year

EL SEGUNDO, Calif.—(BUSINESS WIRE)—August 17, 2011— International Rectifier Corporation (NYSE:IRF) today announced financial results for the fourth quarter (ended June 26, 2011) of its fiscal year 2011.  Revenue for the fourth quarter fiscal year 2011 was $317.2 million, a 6.9% increase from $296.7 million in the third quarter fiscal year 2011 and a 20.3% increase from $263.8 million in the fourth quarter fiscal year 2010.

International Rectifier reported net income of $39.6 million, or $0.55 per fully diluted share for the fourth quarter fiscal year 2011, compared with net income of $49.5 million, or $0.69 per fully diluted share, in the third quarter fiscal year 2011.  The fourth quarter fiscal year 2011 results included a $12.4 million gross tax benefit that benefitted fully diluted earnings per share by $0.18.  The third quarter fiscal year 2011 results included a $6.5 million gross tax benefit and a $3.5 million reversal of restructuring charges, which combined, benefitted third quarter fiscal year 2011 fully diluted earnings per share by $0.14.  For the fourth quarter fiscal year 2010, International Rectifier reported a net income of $29.0 million, or $0.41 per fully diluted share. The fourth quarter fiscal year 2010 results included an $8.5 million gross tax benefit that increased fully diluted earnings per share by $0.12.

Revenue for fiscal year 2011 was $1.18 billion, an increase of 31.4% or $281.3 million over revenue of $895.3 million for the previous fiscal year. Net income of $166.5 million for fiscal year 2011 was an increase of $85.7 million over net income of $80.8 million for the previous fiscal year. Fully diluted earnings per share for fiscal year 2011 were $2.33, an increase of 106% or $1.20 per share over fully diluted earnings per share of $1.13 for the previous fiscal year.

President and Chief Executive Officer Oleg Khaykin stated: “The 2011 fiscal year was a great year for IR.  We achieved strong revenue growth, gross margin expansion and increased profitability compared to the prior fiscal year.  These achievements were driven by a number of factors, including expansion of IR’s market share, strong secular growth in our end-market segments and our strategic decision to continue investments in research and development during the last downturn.  While the current environment may be uncertain, we believe we are in the right markets with the right technologies and are confident in our long-term growth potential. ”

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Gross margin for the fourth quarter fiscal year 2011 was 37.2%, down 2.3% compared with the third quarter fiscal year 2011 and up from 36.1% in the fourth quarter fiscal year 2010.  The fourth quarter fiscal year 2011 gross margin was down compared to the prior quarter as a result of a decrease in higher margin HiRel revenue due to timing of shipments, and an increase in lower margin consumer revenue.

Operating income was $30.6 million or 9.7% of revenue compared with $41.6 million or 14.0% of revenue in the third quarter fiscal year 2011 and up from operating income of $22.2 million or 8.4% of revenue in the fourth quarter fiscal year 2010.

Research and development expenses for the fourth quarter fiscal year 2011 were $32.5 million, up from $30.7 million in the third quarter fiscal year 2011.

Selling, general and administrative expenses for the fourth quarter fiscal year 2011 were $52.1 million, up from $46.7 million in the third quarter fiscal year 2011.

Cash, cash equivalents and marketable investments totaled $499.7 million at the end of the fourth quarter fiscal year 2011, including restricted cash of $2.1 million.

Cash provided by operating activities for the fourth quarter fiscal year 2011 was $62.3 million.

The Company had 69,899,825 shares outstanding at the end of the quarter.

September Quarter Outlook

Oleg Khaykin noted: “With weakened end-market demand, we currently expect September quarter revenue to range from $290 million to $310 million.  Gross margin is expected to increase to about 39%.

“Looking further out, IR continues to see strong design win traction with a number of our products, including energy saving appliance applications, automotive, and servers, as well as in our discrete products. We continue to be optimistic about our long-term growth prospects and are using the near-term weakness to position IR for future growth.”

Segment Table Information/Customer Segments

The business segment tables included with this release for the Company’s fiscal quarters ended June 26, 2011, March 27, 2011 and June 27, 2010, respectively, and fiscal years ended June 26, 2011, and June 27, 2010, respectively, reconcile revenue and gross margin for the Company’s customer segments to the consolidated total amounts of such measures for the Company.  What we refer to as our “customer segments” includes our Power Management Devices, Energy-Saving Products, Automotive Products, Enterprise Power and HiRel reporting segments, and does not include our Intellectual Property reporting segment.

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Annual Report on Form 10-K

The Company expects to file its Annual Report on Form 10-K for the 2011 fiscal year with the Securities and Exchange Commission on Monday, August 22, 2011. This financial report will be available for viewing and download at http://investor.irf.com.

NOTE: A conference call will begin today at 2:00 p.m. Pacific time. CEO Oleg Khaykin and CFO Ilan Daskal will discuss the company’s June quarter results and September quarter outlook. All participants, both in the U.S. and international, may join the call by dialing 706-679-3195 by 1:55 p.m. Pacific time.  In order to join this conference call, participants will be required to provide the Conference Passcode: “International Rectifier”.  Participants may also listen over the Internet at http://investor.irf.com. To listen to the live call, please go to the web site at least 15 minutes early to register, download, and install any necessary audio software.

A taped replay of this call will be available from approximately 6:00 p.m. Pacific time on Wednesday, August 17 through Wednesday, August 24, 2011. To listen to the replay by phone, call 855-859-2056 or 404-537-3406 for international callers and enter reservation number 88785239. To listen to the replay over the Internet, please go to http://investor.irf.com. The live call and replay will also be available on www.streetevents.com.

About International Rectifier

International Rectifier Corporation (NYSE:IRF) is a world leader in power management technology. IR’s analog, digital, and mixed signal ICs, and other advanced power management products, enable high performance computing and save energy in a wide variety of business and consumer applications.  Leading manufacturers of computers, energy efficient appliances, lighting, automobiles, satellites, aircraft, and defense systems rely on IR’s power management solutions to power their next generation products. For more information, go to www.irf.com.

Forward-Looking Statements:

This document contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These statements relate to expectations concerning matters that (a) are not historical facts, (b) predict or forecast future events or results, or (c) embody assumptions that may prove to have been inaccurate.  These forward-looking statements involve risks, uncertainties and assumptions.  When we use words such as “believe,” “expect,” “anticipate,” “will” or similar expressions, we are making forward-looking statements. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give readers any assurance that such expectations will prove correct.  The actual results may differ materially from those anticipated in the forward-looking statements as a result of numerous factors, many of which are beyond our control. Important factors that could cause actual results to differ materially from our expectations include, but are not limited to, reduced demand arising from a decline or volatility in general market and economic conditions or customer

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forecasts; order cancellations due to decreased demand or softening market conditions for customer products; reduced margins from lower than expected factory utilization and higher than expected costs; additional costs or delays in our ability to timely test and implement our new enterprise resource planning (ERP) system which is currently under development;  additional costs or adverse financial effects from implementing our strategic growth initiatives; volatility or deterioration of capital markets; the effects of longer lead times for certain products on meeting demand and any inability by us to satisfy or to timely satisfy customer demand; unexpected costs or delays in implementing our plans to secure and qualify additional manufacturing capacity for our products, including the use of third party contract manufacturers and the purchase and installation of additional manufacturing equipment; the adverse impact of regulatory, investigative and legal actions; increased competition in the highly competitive semiconductor business that could adversely affect the prices of our products or our ability to secure additional business; the effects of manufacturing, operational and vendor disruptions; unexpected delays and disruptions in our supply, manufacturing and delivery efforts due to, among other things, supply constraints, equipment malfunction or natural disasters (including without limitation, any effects from events that may occur from natural and related disasters affecting Japan); delays in launching new technology products; our ability to maintain current intellectual property licenses and obtain new intellectual property licenses; costs arising from pending and threatened litigation or claims; and other uncertainties disclosed in the Company’s reports filed from time to time with the Securities and Exchange Commission, including its most recent reports on Forms 10-K and 10-Q, as filed from time to time.

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INTERNATIONAL RECTIFIER CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENT OF OPERATIONS

(In thousands, except per share data)

(1)       Net income per common share is computed using the two-class method as required by accounting rules.  We do not pay dividends; however, net income must be allocated to unvested restricted stock units (“RSUs”) on which we could pay dividend equivalents.  The amount of net income allocated to these RSUs is excluded from income available to common shareholders in the calculation of earnings per share.  These amounts were $573 thousand and $733 thousand for the three months ended June 26, 2011, and March 27, 2011, respectively, and $2,562 thousand and $465 thousand for the fiscal years ended June 26, 2011 and June 27, 2010, respectively.

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INTERNATIONAL RECTIFIER CORPORATION AND SUBSIDIARIES

CONSOLIDATED BALANCE SHEETS

(In thousands)

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INTERNATIONAL RECTIFIER CORPORATION AND SUBSIDIARIES

CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands)

(1)                               Certain reclassifications have been made to the previously reported amounts to conform to the current presentation.

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For the fiscal years ended June 26, 2011 and June 27, 2010, revenue and gross margin by reportable segments were as follows (in thousands, except percentages):

For the three months ended June 26, 2011 and March 27, 2011, revenue and gross margin by reportable segments were as follows (in thousands, except percentages):

For the three months ended June 27, 2010, revenue and gross margin by reportable segments were as follows (in thousands, except percentages):

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Company contacts:

Investors:

Chris Toth

310.252.7731

Media:

Sian Cummings

310.252.7148

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