BACKGROUND: Oral human papillomavirus (HPV) is associated with a rising incidence of certain head and neck cancers, and oral sex has been associated with oral HPV. This study sought to identify more specific patterns of oral sexual activity, including self-inoculation, that are associated with oral HPV infections in young women. METHODS: A total of 1010 women attending a large university completed a computer-based questionnaire and provided oral specimens that were tested for any oral HPV using a Linear Array assay that detects any HPV as well as 37 HPV genotypes. Twenty-seven women provided additional samples up to 12 months after enrollment. Bivariable and multivariable analyses were conducted to identify oral sexual patterns and other risk factors associated with prevalent oral HPV. RESULTS: Nineteen women had prevalent oral HPV (1.9%), with 10 women (1%) having a type-specific infection. Oral HPV was significantly associated with lifetime coital sex partnership numbers (P = 0.03), lifetime and yearly oral sex partnership numbers (P < 0.01), and hand and/or sex toy transfer from genitals to mouth (P < 0.001). Oral HPV was also associated with greater use of alcohol, cigarettes, marijuana, and sharing of smoking devices, lipstick, or toothbrushes (P < 0.05 for each), with an apparent dose-response for alcohol use and smoking behavior, stratified by number of sexual partners. Of 7 women with prevalent HPV who provided follow-up samples, none had evidence of a persistent type-specific infection. CONCLUSIONS: These data provide additional evidence of transmission of oral HPV from oral sexual activity and also suggest possible transmission from self-inoculation or sharing of oral products.