Cabot Microelectronics Welcomes President George W. Bush to Its Headquarters in Illinois.

AURORA, Ill. -- Cabot Microelectronics Corporation (Nasdaq:CCMP), the world's leading supplier of chemical mechanical planarization (CMP) polishing slurries to the semiconductor industry, hosted a visit by President George W. Bush to its headquarters in Aurora, Illinois this afternoon. The President toured the company to highlight his American Competitiveness Initiative which is designed to encourage innovation and strengthen the nation's ability to compete in the global economy.

"We are extremely honored that the President chose to visit Cabot Microelectronics. We are a technology-driven company that exemplifies the importance of research and development and technical innovation to the U.S. and global economy," said William P. Noglows, Chairman and CEO of Cabot Microelectronics. "As the leader in our field, our technology enables our customers in the semiconductor and data storage industries to produce increasingly sophisticated designs that achieve ever higher levels of performance. We believe our team of world-class scientists, engineers and technologists and our state-of-the-art laboratories are evidence of our dedication to technology leadership. With the research and development activities we conduct, both on our own and in collaboration with partners such as other cutting edge companies and leading universities, we are innovating and winning on a global basis."

ABOUT CABOT MICROELECTRONICS CORPORATION

Cabot Microelectronics Corporation, headquartered in Aurora, Illinois, is the world's leading supplier of CMP slurries used in semiconductor and data storage manufacturing. The company's products play a critical role in the production of advanced semiconductor devices, enabling its customers to manufacture smaller, faster and more complex devices. Along with the company's focus on its core CMP business, it is also looking beyond the semiconductor industry to pursue its vision to "be the world leader in shaping, enabling and enhancing the performance of surfaces". For more information about Cabot Microelectronics Corporation visit www.cabotcmp.com or contact Barbara Ven Horst, Director of Investor Relations at [phone].

SAFE HARBOR STATEMENT

This news release may include statements that constitute "forward looking statements" within the meaning of federal securities regulations. These forward-looking statements include statements related to future sales and operating results, company and industry growth and trends, growth of the markets in which the company participates, international events, product performance, new product introductions, development of new products, technologies and markets, the acquisition of or investment in other entities, and the construction of new facilities by Cabot Microelectronics Corporation. These forward-looking statements involve a number of risks, uncertainties, and other factors, including those described from time to time in Cabot Microelectronics' filings with the Securities and Exchange Commission (SEC), that could cause actual results to differ materially from those described by these forward-looking statements. In particular, see "Risk Factors" in Other Information in our quarterly report on Form 10-Q for the quarter ended December 31, 2005, and "Risks Relating to Our Business" in Management's Discussion and Analysis in our annual report on Form 10-K for the fiscal year ended September 30, 2005, both filed with the SEC. Cabot Microelectronics Corporation assumes no obligation to update this forward looking information.