ATHENAHEALTH SUCCESSFULLY COMPLETES SAS 70 TYPE II EXAMINATION OF ITS NATIONAL SOFTWARE PLATFORM, ATHENANET(R), AND REVENUE CYCLE MANAGEMENT SERVICE OPERATION

Strengthens Commitment to Client Results through Deloitte & Touche Examination of 114 Controls Supporting 20 Control Objectives

WATERTOWN, Mass. (May 20, 2009) – athenahealth, Inc. (NASDAQ: ATHN), a leading provider of Internet-based business services to physician practices, today announced that it has completed a Statement on Auditing Standards No. 70, as amended, (SAS 70) Type II examination, which was performed by Deloitte & Touche LLP (“Deloitte”) over its service operations. Under the SAS 70 Type II examination, Deloitte examined athenahealth’s design of controls and tested the operating effectiveness of such controls related to the Company’s revenue cycle management service operations and its centrally-hosted software platform, athenaNet(R). athenaNet also supports the Company’s electronic health record (EHR) and practice management service offerings and office workflow for approximately 20,000 medical providers in 40 states.

The SAS 70 for athenahealth focused on three areas of the Company’s service operations: Client Services, Claims Operations, and Remittance Services, as well as General Computer Controls. Across these areas, 20 control objectives were examined, testing 114 different controls, including user software and hardware change management procedures, quality assurance testing, security, monitoring and backup procedures.

“We are very pleased to achieve this for our clients’ benefit, and we believe that we are one of the few service providers in our space to do so,” said David E. Robinson, athenahealth’s Chief Operations Officer. “Given the current efforts to bring more health information online, we feel any entity that conducts claims processing on behalf of medical groups should strive to meet the very high standards required to achieve SAS 70 Type II status.”

athenaNet received top ranking for physician practices with two to five physicians in the practice management category in 2008 for the annual Top 20 “Best in KLAS” Awards report. athenaCollector also received “Best in KLAS” for the second straight year in the 26-100 physician practice category and ranked second for medical groups with six-25 physicians. athenahealth service operations processed over 30 million medical claims and posted $3.7 billion in client collections for 2008. As part of its clinical document management service, athenahealth processed approximately 1.9 million clinical documents in the first three months of 2009 for medical practices through its EHR service, athenaClinicalsSM.

Robinson continued, “Although athenahealth has endeavoured to maintain strict internal controls for many years, having a reputable firm like Deloitte conduct an independent examination offers further assurance for our clients and prospects about our service and software platform.”

The SAS 70 Type II examination report is now available to clients of athenahealth. The SAS 70 report may enable athenahealth’s publicly traded and enterprise level client organizations to save time and resources in their own annual audits.

Source: ATHENAHEALTH