IMMEDIATE RELEASE Contact: Mark Johnson Sr. Director, Investor Relations mjohnson@atyrpharma.com 858-223-1163 aTyr Pharma Announces Second Quarter 2017 Operating Results and Provides an Update on Innovative Immunology Pi

aTyr Pharma Announces Second Quarter 2017 Operating Results

and Provides an Update on Innovative Immunology Pipeline

SAN DIEGO - August 14, 2017 - aTyr Pharma, Inc. (Nasdaq: LIFE), a biotherapeutics company engaged in the discovery and development of Physiocrine-based therapeutics to address severe, rare diseases, today announced operating results for the second quarter ended June 30, 2017.

"During the first half of 2017, our team advanced three innovative, first-in-class biologics that harness Physiocrine biology in immunology," said John Mendlein, Ph.D., CEO of aTyr Pharma. "For our Resolaris program, we report favorable safety data from two extension studies in patients with rare muscular dystrophies underscoring the potential for improved clinical outcomes over time based on stabilizing or improving muscle function. In addition, we plan to initiate our first-in-human clinical trial for our iMod.Fc program for ILD. Our third program, ORCA targets a novel, proprietary immuno-oncology pathway using antibodies to change levels of Resokine in tumor settings. We believe tumors utilize Resokine to evade immune system responses. Our Resolaris, iMod.Fc and ORCA programs demonstrate the power and leverage arising from our new insights in immunology and novel therapeutic modalities targeting homeostatic pathways."

Resolaris Program - First Resokine Therapeutic Candidate Based on a Protein Secreted by Muscle

iMod.Fc Program - First Fc Fusion Based Therapeutic Candidate for Lung Diseases

In conjunction with the ATS presentations, aTyr Pharma hosted an educational webinar featuring Dr. Steven D. Nathan, M.D., FCCP, Director of the Advanced Lung Disease Program and Lung Transplant Program at Inova Fairfax Hospital, to provide disease education on interstitial lung diseases that are characterized by an immune component, such as idiopathic pulmonary fibrosis (IPF), sarcoidosis, and chronic hypersensitivity pneumonitis (CHP). The webinar is available on the aTyr Pharma investor website.

Project ORCA - First Antibody Antagonist to a Physiocrine Immunology Pathway

Second Quarter 2017 Financial Results

Research and development expenses were $8.4 million and $11.3 million for the quarters ended June 30, 2017 and 2016, respectively. The decrease of $2.9 million was due primarily to a $2.2 million decrease related to Resolaris clinical trials costs and $0.6 million decrease related to manufacturing costs incurred in support of Resolaris.

General and administrative expenses were $3.5 million and $4.1 million for the quarters ended June 30, 2017 and 2016, respectively. The decrease of $0.6 million was due primarily to a $0.4 million reduction in professional fees.

First Half 2017 Financial Results

Research and development expenses were $17.6 million and $23.3 million for the six months ended June 30, 2017 and 2016, respectively. The decrease of $5.7 million was due primarily to $4.2 million decrease related to manufacturing costs incurred in support of Resolaris and $2.3 million decrease related to Resolaris clinical trials costs. The decrease was partially offset by an increase of $1.0 million related to research and non-clinical development costs incurred for iMod.Fc.

General and administrative expenses were $7.5 million and $8.2 million for the six months ended June 30, 2017 and 2016, respectively. The decrease of $0.7 million was due primarily to a $0.4 million decrease in professional fees.

As of June 30, 2017, aTyr had $57.2 million in cash, cash equivalents and investments and 23.8 million shares of common stock outstanding.

aTyr expects that its cash, cash equivalents and investments will be sufficient to fund its anticipated operations into the third quarter of 2018.

aTyr Pharma is engaged in the discovery and clinical development of innovative medicines for patients suffering from severe, rare diseases using its knowledge of Physiocrine biology, a newly discovered set of immunological and physiological pathways. To date, the Company has generated three innovative therapeutic programs based on its knowledge of Physiocrine biology in three different therapeutic areas and three different biologic modalities. aTyr has built an intellectual property estate, to protect its pipeline, comprising over 220 issued patents or allowed patent applications that are owned or exclusively licensed, including over 300 potential Physiocrine-based protein compositions. aTyr's key programs are currently focused on severe diseases characterized by immune imbalance for which there are currently limited or no treatment options. For more information, please visit http://www.atyrpharma.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Litigation Reform Act. Forward-looking statements are usually identified by the use of words such as "anticipates," "believes," "estimates," "expects," "intends," "may," "plans," "projects," "seeks," "should," "will," and variations of such words or similar expressions. We intend these forward-looking statements to be covered by such safe harbor provisions for forward-looking statements and are making this statement for purposes of complying with those safe harbor provisions. These forward-looking statements, including statements regarding, the potential and potential therapeutic benefits of Resolaris , iMod.Fc, or potential product candidates from Project ORCA, the ability of the Company to successfully advance its pipeline or product candidates, undertake certain development activities (such as clinical trial enrollment and the conduct of clinical trials) and accomplish certain development goals and the timing of such activities and development goals, the timing of initiation of additional clinical trials, the scope and strength of our intellectual property portfolio, our ability to receive regulatory approvals for, and commercialize, our product candidates and of reporting results from our clinical trials, and our projected cash expenditures reflect our current views about our plans, intentions, expectations, strategies and prospects, which are based on the information currently available to us and on assumptions we have made. Although we believe that our plans, intentions, expectations, strategies and prospects as reflected in or suggested by those forward-looking statements are reasonable, we can give no assurance that the plans, intentions, expectations or strategies will be attained or achieved. Furthermore, actual results may differ materially from those described in the forward-looking statements and will be affected by a variety of risks and factors that are beyond our control including, without limitation, risks associated with the discovery, development and regulation of our Physiocrine-based product candidates, as well as those set forth in our most recent Annual Report on Form 10-K for the year ended December 31, 2016 and in our other SEC filings. Except as required by law, we assume no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise.