NxStage(R) Announces the Sale of 3.2 Million Shares of Common Stock

Wednesday November 17, 2010

LAWRENCE, Mass., Nov. 17, 2010 /PRNewswire via COMTEX/ — NxStage Medical, Inc. (Nasdaq: NXTM) today announced the sale of 3.2 million shares of its common stock pursuant to an underwriting agreement with Canaccord Genuity Inc. The closing price of the Company’s common stock on the Nasdaq Global Market on November 17, 2010 was $21.38 per share.

The Company expects to use the proceeds from the sale of the shares for working capital and general corporate purposes. Closing of the offering is expected to occur on or about November 23, 2010, subject to customary closing conditions. In addition, the Company has granted Cannacord Genuity Inc., the sole bookrunner for the offering, a 30-day option to purchase up to an additional 480,000 shares of common stock to cover over-allotments, if any.

The offering is being made pursuant to an effective shelf registration statement. Before you invest, you should read the base prospectus in the shelf registration statement and other documents the Company has filed with the Securities and Exchange Commission for more complete information about the Company and this offering. Copies of the prospectus supplement and the accompanying prospectus, when available, may be obtained by sending a request to the offices of Canaccord Genuity Inc., Attn: Syndicate Department, 99 High Street, 12th Floor, Boston, MA 02110, phone: 617-371-3900, email: usecm@canaccordgenuity.com. Alternatively, you may get these documents for free by visiting EDGAR on the SEC website at http://www.sec.gov/.

This press release shall not constitute an offer to sell, or the solicitation of an offer to buy, any of the securities, nor shall there be any sale of these securities, in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

About NxStage Medical

NxStage Medical, Inc. (Nasdaq: NXTM) is a medical device company, headquartered in Lawrence, Massachusetts, USA, that develops, manufactures and markets innovative products for the treatment of ESRD and acute kidney failure. For more information on NxStage and its products, please visit the company’s website at http://www.nxstage.com/.

Forward-Looking Statements

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this release that are not clearly historical in nature are forward-looking, and the words anticipate, believe, expect, estimate, plan, and similar expressions are generally intended to identify forward-looking statements. Forward-looking statements include statements about the use of proceeds. Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors including factors that are discussed in NxStage’s filings with the Securities and Exchange Commission, including its Quarterly Report on Form 10-Q for the quarter ended September 30, 2010. NxStage is under no obligation to (and expressly disclaims any such obligation to) update or alter its forward-looking statements, whether as a result of new information, future events or otherwise.

Contact:

Kristen K. Sheppard, Esq.

Investor Relations

ksheppard@nxstage.com

SOURCE NxStage Medical, Inc.