What is already known about this topic? Each year, approximately 350 new human immunodeficiency virus (HIV) infections are diagnosed in U.S. military service members, with most diagnoses occurring among men who have sex with men (MSM). What is added by this report? Among 769 service members prescribed preexposure prophylaxis (PrEP) during February 1, 2014–June 10, 2016, 87% were MSM. In a survey of health care providers, 49% rated their knowledge of PrEP as poor, and 29% reported ever having prescribed PrEP. What are the implications for public health practice? Strategies for reducing barriers to receipt of HIV prevention and care services include patient self-referrals for PrEP evaluations and development of new health policy to provide universal access to the provider, laboratory, and pharmacy services required for an effective PrEP program.