Cubist Pharmaceuticals to Present at September Investor Conferences; Presentations at the Thomas Weisel Partners Healthcare Conference, Bear Stearns 19th Annual Healthcare Conference, and the UBS 2006 Global Life Sciences Conference.

LEXINGTON, Mass. -- Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today announced that senior management will present at three September investor conferences. On Wednesday, September 6th, at 10:55 A.M. ET, David W. J. McGirr, SVP and CFO will present at the Thomas Weisel Partners Healthcare Conference being held at the Four Seasons Hotel in Boston. Michael Bonney, President and CEO will present on Tuesday, September 12th, at 9:00 A.M. ET, at the Bear Stearns 19th Annual Healthcare Conference being held at the Grand Hyatt in New York City. David McGirr will also present at the UBS 2006 Global Life Sciences Conference which will be held at the Park Avenue at Grand Central in New York City on September 25th at 8:00 A.M. ET. Each presentation will include a discussion of the company's business activities, financial outlook, and current news.

A live webcast of each presentation will be accessible through a link on the front page of Cubist's website at www.cubist.com and also in the Investor Relations Conference Calendar section of the website. The presentations will be archived and available after the event for a period of 30 days.

About Cubist

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the research, development and commercialization of antiinfective products that address unmet medical needs in the acute care environment. In the U.S., Cubist markets CUBICIN(R) (daptomycin for injection), the first antibiotic in a new class of antiinfectives called lipopeptides. The Cubist product pipeline includes our lipopeptide program and our natural products screening program. Cubist is headquartered in Lexington, MA. Additional information can be found at Cubist's web site at www.cubist.com.

Cubist Safe Harbor Statement

Statements contained herein that are not historical fact may be forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, and such statements are subject to a variety of risks and uncertainties. There are a number of important factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements made by Cubist. These factors include, but are not limited to: (i) whether we will receive, and the potential timing and scope of, regulatory approvals or clearances to market CUBICIN in other countries and for additional indications in the United States and other countries pursuant to our currently planned filings and any filings we determine to make in the future, which filings are subject to approval by the applicable regulatory agency or agencies, regardless of our confidence in the results of the clinical trials supporting such filings; (ii)the level of acceptance of CUBICIN by physicians, patients, third party payors and the medical community; (iii)any changes in the current or anticipated market demand or medical need for CUBICIN; (iv)competition, particularly with respect to CUBICIN; (v)whether the U.S. Food and Drug Administration, or FDA, accepts proposed clinical trial protocols that may be achieved in a timely manner; (vi) our ability to conduct successful clinical trials in a timely manner; (vii) the ability of our third party manufacturers, including our single source provider of API to manufacture sufficient quantities of CUBICIN in accordance with current Good Manufacturing Practices and other requirements of the regulatory approvals for CUBICIN and at an acceptable cost; (viii) our dependence upon collaborations with our partners; (ix) our ability to finance our operations; (x) the effectiveness of our expanded sales force; (xi) potential costs resulting from product liability or other third party claims; (xii) our ability to protect our proprietary technologies; (xiii) our ability to integrate successfully the operations of any business we may acquire and the potential impact of any future acquisition on our financial results; (xiv) our ability to discover, acquire or in-license drug candidates and develop and achieve commercial success for drug candidates; and (xv) a variety of risks common to our industry, including ongoing regulatory review, litigation relating to intellectual property, and legislative or regulatory changes.

Additional factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements are contained in Cubist's recent filings with the Securities and Exchange Commission, including those factors discussed under the caption "Risk Factors" in such filings.

Cubist and CUBICIN are registered trademarks of Cubist Pharmaceuticals, Inc.