The provision of medical care through telemedicine services is a promising solution to the problems associated with cost, quality, and access within the U.S. healthcare system. Telemedicine programs provide specialty medical services to patients in rural or remote areas, who otherwise would have to travel significant distances to receive similar healthcare. Significant investments have been made towards telemedicine equipment, personnel, and technology. While reports of patient satisfaction remain high with telemedicine services, there is a need for more rigorous evaluations of telemedicine outcomes and cost. However, many challenges persist in telehealth research. Retrospective examination of large payer claims databases related to telehealth outcomes and cost rely on the use of the telehealth GT modifier to the appropriate CPT or HCPCS code. However, due to a variety of factors (e.g. coding errors, misunderstanding of billing practices, insurance-level policies requiring claim submission without the modifier, and a number of telehealth services that are currently not reimbursable) the availability of comprehensive telehealth claims data is limited. As a result, many telehealth studies rely on the use of patient registry or electronic medical record data. These sources present their own unique set of challenges. During a telehealth visit the patient and provider are geographically separated. In many cases, the patient is located within a different organization than the provider. The consulting provider’s organization is dependent on the referring patient’s organization to share information on patient outcomes. This process frequently results in missing and incomplete data. This session will explore the methodological challenges related to telehealth research.