The prevalence and risk factors for oral human papillomavirus (HPV) infection are unknown, despite evidence for an etiological role for HPV in oral cancers. Oral samples from human immunodeficiency virus (HIV)-seronegative (n=396) and HIV-seropositive (n=190) adults were tested for HPV DNA. High-risk HPV infections were present in 2.1% of tonsil and 6.3% of oral-rinse specimens. The prevalence of oral high-risk HPV infection was greater in HIV-seropositive individuals (13.7% vs. 4.5%; P<.001). In multiple logistic regression, odds of oral HPV infection increased with age, male sex, and herpes simplex virus (HSV)-2 seropositivity in HIV-seronegative individuals and with CD4 cell count <200 cells/mL, HSV-2 seropositivity, oral mucosal abnormalities, and >1 oral sex partner during the previous year (odds ratio, 12.8; 95% confidence interval, 3.1-52.7) among HIV-seropositive individuals. HPV type 16, which is present in most HPV-associated tonsillar cancers, was the most prevalent high-risk oral HPV infection.