NxStage Announces Strategic Business Alliance with Asahi Kasei Kuraray Medical

- Alliance Establishes Partnership with Leading Renal Products Company in Asia

- Collaboration Expected to Yield Gross Margin Improvement and Accelerate Path
to Profitability

- Financing Provided in Connection with Alliance Significantly Improves
Balance Sheet and Cash Flow

LAWRENCE, Mass., May 18 /PRNewswire-FirstCall/ -- NxStage Medical, Inc.
(Nasdaq: NXTM), a leading manufacturer of innovative dialysis products, today
announced its plans to form a strategic business alliance with Asahi Kasei
Kuraray Medical, ("Asahi"), a leading medical supply company headquartered in
Japan. The signed agreements between the partners are multi-faceted, but most
importantly leverage NxStage's production expertise in its existing dialyzer
manufacturing facility in Germany and Asahi's high performance polysulfone
hollow-fiber membranes. In addition, Asahi will provide NxStage with $40
million of debt financing to pay off its entire debt obligation owed under its
GE credit facility.

The alliance combines the complementary strengths of the two partners in
innovative and competitive technology, product development, and market
presence. This transaction is expected to enable both companies to accelerate
their global growth strategy through mutual synergy.

Elements of the Alliance:

Dialyzer Assembly
NxStage will assemble and label its dialyzers for Asahi under the Asahi name
brand at NxStage's facilities in Germany. Asahi will sell the dialyzers
exclusively in Asia and non-exclusively in rest of world; however, NxStage is
retaining all its rights in North America. When Asahi desires additional
capacity from NxStage, Asahi shall fund the construction of a new facility to
provide both parties with additional dialyzer production capacity. The new
facility would be owned by Asahi and operated by NxStage. By collaborating in
dialyzer assembly, both parties expect to realize cost savings.

Licensing
NxStage will grant Asahi a royalty-free license to its production technology
to make and sell NxStage's current dialyzer design exclusively in Asia and
non-exclusively in rest of world; however, NxStage is retaining all its rights
in North America. NxStage will also license certain rights for Streamline
blood tubing set technology to Asahi under similar conditions. Any
improvements obtained through the combination of the dialyzer manufacturing or
bloodline technologies of the two companies are to be mutually cross-licensed
on similar terms.

Hollow-Fiber Membrane Supply
Asahi will supply its high performance polysulfone hollow-fiber membrane to
NxStage for NxStage branded products in North America. Consistent with our
obligations, NxStage will continue to purchase fiber from its current supplier
for NxStage System One filters.

Financial Backing
Asahi will provide NxStage with $40 million of debt financing on competitive
terms, including an 8% interest rate (NxStage's current rate under the GE
facility is 11%), with 50% of the interest deferred to maturity. The four
year loan includes no financial covenants and the debt may be prepaid by
NxStage without penalty at anytime. However, if the loan goes to maturity,
Asahi will have the option, subject to certain limitations, to be repaid in
shares of NxStage common stock. The debt includes a balloon principal
repayment and will be secured by NxStage assets other than cash, accounts
receivables, inventory or field equipment. The debt agreement also provides
NxStage the ability to borrow up to $40 million from other lenders. Part of
the proceeds will be used to pay off NxStage's $28 million owed under its GE
credit facility plus prepayment and other transaction fees. Remaining
proceeds will be used for operating purposes.

Other Collaboration
Joint business development will be pursued in areas as mutually agreed upon
between the two companies. Possible areas include the development of
therapeutic apheresis systems using NxStage's technology, collaboration on raw
materials sourcing, and possible joint hemodialysis systems development
programs. NxStage also granted Asahi a right of first negotiation for
exclusive distribution rights of the NxStage System One in Asia.

"Our relationship with one of the largest renal product companies in Asia is
an important step for NxStage as we extend our commercial operations
globally," stated Jeffrey H. Burbank, Chief Executive Officer of NxStage
Medical. "I believe this transaction will accelerate our path to
profitability. We are enthusiastic that this relationship with Asahi will
deliver significant value to our shareholders, strengthen our balance sheet,
and create growth opportunities in 2010 and beyond."

"NxStage has proven its ability to produce high-performing, low-cost dialyzers
in the competitive renal products market," stated Yasuyuki Yoshida, Chief
Executive Officer and President of Asahi Kasei Kuraray Medical. "We are
aligning ourselves with a diversified leader in US renal care with superb
products and an impressive track record. We believe this alliance leverages
Asahi Kasei Kuraray Medical's leadership position, providing us a strong and
growing partner for our world class fiber technology."

The agreements with Asahi are conditioned upon NxStage obtaining a payoff
letter and associated documentation from the lenders under its GE credit
facility.

Conference Call and Webcast Information
NxStage management will hold a conference call to discuss this new alliance
today, Monday, May 18, 2009 at 5:00 p.m. Eastern Time. To listen to the
conference call, please dial 800-901-5259 (domestic) or 617-786-4514
(international). The passcode is 54617836. The call will also be webcast
LIVE and can be accessed via the investor relations section of NxStage's
website at www.nxstage.com/ir.cfm.

A replay of the conference call will be available 3 hours after the start of
the call through June 1, 2009. To access the replay dial 888-286-8010
(domestic) or 617-801-6888 (international) and enter passcode 31022930. An
online archive of the conference call can be accessed via the investor
relations section of NxStage's website at www.nxstage.com/ir.cfm.

About Asahi Kasei Kuraray Medical
Asahi Kasei Kuraray Medical is dedicated to the advancement of world-leading
technology in the fields of hemodialysis, therapeutic apheresis, transfusion
therapy, and virus removal for biotherapeutic products. Asahi Kasei Kuraray
Medical works to introduce innovative therapies for intractable diseases by
extending the frontiers of medical devices and system, combining its core
technology in functional materials for membrane filtration and selective
adsorption with advanced pharmacology, chemistry, and mechanical engineering.
The group is structured with Asahi Kasei Corporation as a holding company, and
core operating companies as wholly owned subsidiaries to perform business in
each of the separate industry fields. Asahi Kasei Kuraray Medical and Asahi
Kasei Medical are the core operating companies for medical and biotech device
operations.

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 End Stage Renal Disease
(ESRD) and acute kidney failure. To see how NxStage is changing renal care for
patients click here 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. Examples of these forward-looking statements include statements as
to the anticipated acceleration of profitability, improvements in gross
margins, improvements in balance sheet, improvements in cash flow, anticipated
growth opportunities, and other expected benefits of the Asahi strategic
alliance as well as the anticipated closing of this alliance. All
forward-looking statements involve risks, uncertainties and contingencies,
many of which are beyond NxStage's control, which may cause actual results,
performance, or achievements to differ materially from anticipated results,
performance or achievements, including market acceptance and demand for
NxStage's dialyzers and ability to achieve cost reductions and other
anticipated benefits of the alliance, and certain other factors that may
affect future operating results and which are detailed in NxStage's filings
with the Securities and Exchange Commission, including the Quarterly Report on
Form 10-Q for the quarter ended March 31, 2009. In addition, the statements in
this press release represent NxStage's expectations and beliefs as of the date
of this press release. NxStage anticipates that subsequent events and
developments may cause these expectations and beliefs to change. However,
while NxStage may elect to update these forward-looking statements at some
point in the future, it specifically disclaims any obligation to do so,
whether as a result of new information, future events, or otherwise. These
forward-looking statements should not be relied upon as representing NxStage's
expectations or beliefs as of any date subsequent to the date of this press
release.

Contacts:
Kristen K. Sheppard, Esq.
VP, Investor Relations
978-609-5842
ksheppard@nxstage.com

SOURCE NxStage Medical, Inc.

Kristen K. Sheppard, Esq., VP, Investor Relations of NxStage Medical, Inc.,
+1-978-609-5842, ksheppard@nxstage.com