Orogenital transmission of human immunodeficiency virus (HIV) is considered to be inefficient, and infectious HIV is rarely detected in saliva. To evaluate the posterior oropharynx as a source of HIV shedding, we studied 64 HIV-infected men who have sex with men in Seattle, Washington, and Lima, Peru. In multivariate analysis, receipt of antiretroviral therapy, higher CD4 cell count, and history of tonsillectomy were predictors of lower pharyngeal HIV RNA levels.