ARYx Therapeutics Schedules First Quarter 2008 Results and Earnings Call and Clarifies Expiration of Lock-Up Period

ARYx Therapeutics, Inc. (NASDAQ:ARYX), a biopharmaceutical company, announced today a conference call to discuss first quarter 2008 results will be held on Tuesday, May 13, 2008 at 8:00 a.m. Pacific Time.

The dial-in information for the call is as follows:

Dial In: 866-356-4123

Dial In (International): 617-597-5393

Passcode: 83320446

Preregistration is not required. This call is also being webcast by Thomson/CCBN and can be accessed at ARYx Therapeutics’ web site at www.aryx.com or through Thomson at www.earnings.com. Replays of the call will be available through May 27, 2008 by dialing 888-286-8010 (617-801-6888 Internationally), passcode 71346489.

Due to the timing of ARYx Therapeutics’ earnings release, the lock-up agreements between the underwriters and certain ARYx Therapeutics stockholders, which were entered into in conjunction with its initial public offering (IPO), will automatically be extended an additional 18 days from the date the Company reports results for the first quarter, as described in the lock-up agreement. As a result of this automatic extension, no shares subject to the IPO lock-up agreement may be traded prior to Saturday, May 31, 2008, the first trading day after its expiration, unless such lock-up restriction is waived in writing by the underwriters for the ARYx Therapeutics IPO. The lock-up period had originally been due to expire on Tuesday, May 6, 2008.

About ARYx Therapeutics

ARYx Therapeutics is a biopharmaceutical company focused on developing a portfolio of internally discovered products designed to eliminate known safety issues associated with well-established, commercially successful drugs. ARYx uses its RetroMetabolic Drug Design(TM) technology to design structurally unique molecules that retain the efficacy of these original drugs but are metabolized through a potentially safer pathway to avoid specific adverse side effects associated with these compounds. ARYx currently has three products in Phase 2 clinical trials: ATI-7505 for the treatment of various gastrointestinal disorders; ATI-5923 for the treatment of patients at risk for the formation of dangerous blood clots; and ATI-2042 for the treatment of atrial fibrillation. A fourth product, ATI-9242 for the treatment of schizophrenia and other psychiatric disorders, is in Phase 1 development. Please visit our web site at www.aryx.com for additional information.

Forward Looking Statement

This press release contains forward-looking statements, including, without limitation, statements related to the timing and availability of clinical results, the initiation of new clinical trials, the completion of preclinical work, the ability of preclinical packages to lead to further clinical trials, the ability of a product candidate to be more predictable than currently available therapies regarding dosing and response to treatment, and the ability of a product candidate to avoid the dangers existing in currently available therapies. Words such as ” expects,”"potential,”"will be studied,”"will receive,”"will be randomly assigned,”"will continue,”"can result,” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon the company’s current expectations. Forward-looking statements involve risks and uncertainties. The company’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 risk that collaborative arrangements will likely place the development of our product candidates outside of our control, the risk that we may have to alter our development and commercialization plans if collaborative relationships are not established for ATI-5923 and ATI-2042, the risk that the company may be unable to raise additional capital when needed which would force the company to delay, reduce or eliminate product development programs, the risk that any failure or delay in commencing or completing clinical trials for the company’s product candidates could severely harm our business, and the risk that third party manufacturers could delay or prevent the clinical development of our product candidates. These and other risk factors are discussed under “Risk Factors” and elsewhere in the company’s Annual Report on Form 10-K for the year ended December 31, 2007. The company expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein.