Cubist Pharmaceuticals to Announce First Quarter 2006 Financial Results on Wednesday, April 19th, 2006.

LEXINGTON, Mass. -- Conference Call to be Held 5:00 p.m. EDT

Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) will issue its first quarter financial results at 4:00 p.m. EDT on Wednesday, April 19, 2006. In connection with this announcement, Cubist will host a conference call and live audio webcast (with slides) at 5:00 p.m. EDT that same day to discuss its first quarter financial results, the company's business activities, and financial outlook.

As always, the quarterly earnings call will be available via phone and webcast. The dial-in information is listed below. To access the webcast, please log on to the Company's website at www.cubist.com at least 15 minutes prior to the start of the call to ensure adequate time for any software downloads that may be required.

A replay of the webcast and teleconference will be available on the Company's website approximately three hours after the call.

CONFERENCE CALL & WEBCAST INFORMATION
Cubist will host a conference call and live audio webcast on 4/19/06
at 5:00 p.m. EDT to discuss its first quarter financial results, the
company's business activities, and financial outlook.

LIVE DOMESTIC & CANADA CALL-IN:  [phone]
LIVE INTERNATIONAL CALL-IN:  [phone]
24-HOUR REPLAY DOMESTIC & CANADA:  [phone]
24-HOUR REPLAY INTERNATIONAL:  [phone]
REPLAY Account # 286 & Conference ID # 196688 (both are needed)
CALL WILL ALSO BE BROADCAST LIVE, LISTEN ONLY, VIA THE INTERNET AT:
www.cubist.com
Replay will be available for 30 days via the Internet.

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. CUBICIN is currently the only once-daily bactericidal antibiotic approved in the U.S. with activity against both methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA) in complicated skin and skin structure infections. In September, 2005, Cubist submitted a supplemental New Drug Application (sNDA) for approval to add S. aureus bacteremia with known or suspected endocarditis to the indication statement for CUBICIN. The FDA granted this application priority review. On March 6, the Anti-Infective Drugs Advisory Committee recommended approval of an expanded label for CUBICIN. On March 24th, the FDA issued an approvable letter, with action on a label expected by late May. The Cubist product pipeline includes our lipopeptide program, the product candidate HepeX-B and our natural products screening program. Cubist is headquartered in Lexington, MA.

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 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 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 bulk drug substance, to manufacture sufficient quantities of CUBICIN in accordance with Good Manufacturing Practices and at an acceptable cost; (viii) our dependence upon pharmaceutical and biotechnology collaborations; (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 discover or in-license drug candidates and develop and achieve commercial success for drug candidates; and (xiv) 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.; HepeX-B is a trademark of XTL Biopharmaceuticals Ltd.

Additional information can be found at Cubist's web site at www.cubist.com