Despite increased awareness and greater societal acceptance of people who are transgender, the inability to systematically identify and study the transgender population greatly hampers our capacity to conduct meaningful analysis of this group. Furthermore, population-based studies of transgender individuals entitled to Medicare due to age (65 and older), disability, or end-stage renal disease are nonexistent, demonstrating the need for more and better research focused on sexual and gender minorities, including the transgender population. We explore the use of Medicare billing data from the Centers for Medicare & Medicaid Services (CMS), the federal agency that administers the Medicare and Medicaid programs, to identify and describe Medicare’s transgender population.