Last month marked the three-year anniversary of the U.S. Food and Drug Administration's approval of tenofovir/emtricitabine (Truvada) for use as PrEP, but in many clinical settings it remains heavily underutilized. Kenneth H. Mayer, M.D., and Douglas S. Krakower, M.D., explore the reasons behind PrEP's slow adoption in an editorial commentary published online on Aug. 13 in Clinical Infectious Diseases. "[T]he challenges posed by unsupportive health insurance environments may become one of the major impediments remaining for PrEP to be scaled up at a sufficient level to radically decrease the number new HIV infections across the United States," they warn.