XNPT Xenoport, Inc.

XenoPort, Inc. (Nasdaq:XNPT) announced today that it will present data on XP23829, an investigational prodrug of monomethyl fumarate (MMF), at the 2014 Joint ACTRIMS-ECTRIMS Meeting in Boston. Data being presented include the results from a clinical trial evaluating the safety, tolerability and pharmacokinetics of XP23829.

The title of the poster, presentation time and location are as follows:

XP23829

• Steady state pharmacokinetics and blood lymphocyte responses in healthy subjects dosed with XP23829, a novel fumaric acid ester for multiple sclerosis;

Poster 958; Friday, September 12, 2014; 2:45 p.m. ET Location: Hall C, Poster Exhibition area, 2nd Floor, Hynes Convention Center

About XP23829

XP23829, an experimental drug discovered and currently under development by XenoPort, is a fumaric acid ester compound that is a prodrug of MMF. XenoPort is currently evaluating XP23829 in a Phase 2 clinical trial as a potential treatment for moderate-to-severe chronic plaque-type psoriasis, and XP23829 may be a potential treatment for relapsing forms of multiple sclerosis (MS).

XP23829 is protected by a composition-of-matter patent that currently has an expiration date of 2029.

About XenoPort

XenoPort, Inc. is a biopharmaceutical company focused on developing and commercializing a portfolio of internally discovered product candidates for the potential treatment of neurological disorders. XenoPort is currently commercializing HORIZANT® (gabapentin enacarbil) Extended-Release Tablets in the United States and developing its novel fumaric acid ester product candidate, XP23829, as a potential treatment for patients with moderate-to-severe chronic plaque-type psoriasis and/or relapsing forms of MS. REGNITE® (gabapentin enacarbil) Extended-Release Tablets is being marketed in Japan by Astellas Pharma Inc. XenoPort recently granted exclusive world-wide rights for the development and commercialization of its clinical-stage oral product candidate, arbaclofen placarbil, to Reckitt Benckiser Pharmaceuticals, Inc. for all indications. XenoPort's pipeline of product candidates also includes a potential treatment for patients with Parkinson's disease.

To learn more about XenoPort, please visit the website at www.XenoPort.com.

Forward-Looking Statements

This press release contains “forward-looking” statements, including, without limitation, all statements related to advancing the development of XP23829; the suitability of XP23829 as a potential treatment for moderate-to-severe chronic plaque-type psoriasis and/or relapsing forms of MS; and the therapeutic and commercial potential of XP23829. Any statements contained in this press release that are not statements of historical fact may be deemed to be forward-looking statements. Words such as “may,” “potential,” “will” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon XenoPort's current expectations. Forward-looking statements involve risks and uncertainties. XenoPort's actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of these risks and uncertainties, which include, without limitation: the difficulty and uncertainty of pharmaceutical product development and the uncertain results and timing of clinical trials and other studies; XenoPort’s ability to successfully conduct clinical trials in the anticipated timeframes, or at all; the risk that XP23829 will require significant additional clinical testing prior to any possible regulatory approvals and failure could occur at any stage of its development; the uncertainty of the regulatory review process and other regulatory requirements; the uncertainty of protecting and expanding XenoPort's intellectual property rights, including the risk that patent rights may not provide XenoPort with sufficient protection against competitive products or otherwise cover commercially valuable products or processes; XenoPort's dependence on potential future collaborative partners; and the uncertain therapeutic and commercial value of XenoPort's product candidates. These and other risk factors are discussed under the heading “Risk Factors” in XenoPort’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2014 filed with the Securities and Exchange Commission on August 7, 2014. XenoPort expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in the company's expectations with regard thereto or any change in events, conditions or circumstances on which any such statements are based.

HORIZANT, REGNITE and XENOPORT are registered trademarks of XenoPort, Inc.

XNPT2G

XenoPort, Inc.Jackie Cossmon, 408-616-7220ir@XenoPort.com