Exhibit 99.1

CYMER REPORTS FIRST QUARTER 2011 OPERATING RESULTS

SAN DIEGO, Calif., April 21, 2011 - Cymer, Inc. (Nasdaq: CYMI), the world’s leading supplier of light sources used by chipmakers to create advanced semiconductor chips, today announced operating results for the first quarter ended March 31, 2011.

For the first quarter of 2011:

Commenting on results, Bob Akins, Cymer’s chief executive officer, said, “The first quarter of 2011 was a very productive period for the company. Key customer deep ultraviolet (DUV) selections awarded in the second half of 2010 began to translate into an increased level of light source shipments in the first quarter of 2011, and first quarter gross pulse utilization remained high. We continued to increase our extreme ultraviolet (EUV) investment, adding technical and operational capability in support of the development of our 3100 and 3300 source technology. We continued our focus on ramping our TCZ manufacturing capability to fulfill recently received orders.”

In the first quarter of 2011, the company shipped 50 light sources, of which 28 were ArF immersion, 19 were KrF, and three were ArF dry, and the company installed 46 light sources at chipmaker locations. Gross profit was $79.5 million for the first quarter of 2011, yielding a 51.5 percent gross margin. Total operating expenses, which include research and development and selling and administrative expenses, were $43.9 million. Total operating income was $35.7 million or 23.1 percent of revenue. The first quarter effective tax rate was 21 percent. As of March 31, 2011, cash and investments totaled approximately $242 million.

DUV bookings for the first quarter of 2011 totaled $161.5 million, resulting in a DUV book-to-bill ratio of 1.05. Fifty-seven percent of the DUV bookings in the first quarter were ArF immersion, 41 percent were KrF, and two percent were ArF dry. The company ended the quarter with a DUV backlog of $71.0 million, with ArF immersion light sources comprising approximately 83 percent of the value of sources in backlog.

– more –

Company Outlook

Commenting on the outlook, Akins stated, “We are well positioned for continued growth in 2011. We are pleased to have received a multi-unit order valued at over two hundred million dollars for the next generation of EUV light sources that will support the ASML NXE:3300 lithography system aimed at high-volume production of semiconductor devices at sub-20 nanometer nodes. We believe EUV will be a major impetus of future growth for Cymer and are therefore proportionately accelerating the rate of our investment in engineering, program management, field support and factory capacity keeping with planned source performance targets and increasing customer demand. In addition, we received a volume order for TCZ Gen 5.5 systems from a leading Asian flat panel display manufacturer. We now have orders for TCZ Gen 4 and Gen 5 systems in excess of $30 million, with options for additional systems in 2012.”

Akins further commented, “We anticipate gross pulse utilization to remain high in the second quarter of 2011. In our continuing effort to extend OnPulse value, this month we completed the acquisition of eDiag Solutions, a privately held company based in Seoul, Korea, for $15.0 million in cash, $6 million of which was paid at closing in the second quarter. eDiag provides a compelling portfolio of software solutions for lithography source performance data mining and analytics which complements our OnPulse offerings.”

Based on information available at this time, Cymer is providing the following guidance for the second quarter of 2011:

Cymer’s management will hold a conference call at 2:00 pm (PDT) today, April 21, 2011, to discuss first quarter operating results and second quarter 2011 guidance. This press release, the conference call and accompanying slides may be accessed on the investor relations page of the company’s Web site at www.cymer.com.

-more-

Forward Looking Statements

Statements in this press release that are not strictly historical in nature are forward-looking statements. These statements include, but are not limited to statements regarding the development of the company’s EUV source technology, the company’s development of and manufacturing capability for its silicon crystallization tool for the flat panel display industry, the industry’s transition to EUV lithography and the statements under the caption “Company Outlook” above. These statements are predictions based on current information and expectations and involve a number of risks and uncertainties. In addition, statements regarding backlog and book-to-bill ratios should not be read as predictions or projections of future performance. Actual events or results may differ materially from those projected in any of such statements due to various factors, including but not limited to: the demand for semiconductors in general, and, in particular, for leading-edge devices with smaller geometries; cyclicality in the market for semiconductor manufacturing equipment; the timing of customer orders, shipments and acceptances; delays or cancellations by customers of their orders; the performance and market acceptance of the company’s new products or technologies; new and enhanced product offerings by competitors; the company’s ability to meet its production and product development schedules; the rate at which semiconductor manufacturers adopt new technologies and purchase and take delivery of photolithography tools from the company’s customers; the company’s ability to secure adequate supplies of critical components for its advanced products; the company’s ability to manage its expense levels and unanticipated expenses; the company’s ability to achieve its forecasted gross margin which includes its ability to absorb manufacturing costs; the company’s ability to align its cost structure with forecasted business levels; the company’s ability to manage its foreign currency exposure; the performance and conditions in the United States and world financial markets; the policies and actions of the United States and other governments; and general economic conditions. For a discussion of these and other factors which may cause our actual events or results to differ from those projected, please refer to the company’s most recent annual report on Form 10-K and quarterly reports on Form 10-Q, as well as other subsequent filings with the Securities and Exchange Commission (SEC). You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. All forward-looking statements are qualified in their entirety by this cautionary statement, and the company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date of this press release.

About Cymer

Cymer, Inc. (Nasdaq: CYMI) is the market leader in developing light sources, used by chipmakers worldwide to pattern advanced semiconductor chips, and is pioneering a new silicon crystallization tool for the flat panel display industry. Cymer’s light sources have been widely adopted by the world’s top chipmakers and the company’s installed base comprises approximately 3,750 systems. Continuing its legacy of leadership, Cymer is currently pioneering the industry’s transition to EUV lithography, the next viable step on the technology roadmap for the creation of smaller, faster chips. The company is headquartered in San Diego, Calif., and supports its customers from numerous offices around the globe. Cymer maintains a Web site to which it regularly posts press releases, SEC filings, and additional information about Cymer. Interested persons can also subscribe to automated e-mail alerts or RSS feeds. Please visit www.cymer.com.

Cymer and all other Cymer product or service names used herein are either registered trademarks or trademarks of Cymer, Inc. Any other marks mentioned herein are the property of their respective holders.

-more-

CYMER, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)

(in thousands, except per share data)

-more-

CYMER, INC.

CONSOLIDATED BALANCE SHEETS (UNAUDITED)

(in thousands, except share data)

-more-

CYMER, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)

(in thousands)

###