The incidence, location, and morphologic appearances of human papillomavirus oral lesions in patients with genital condylomatosis were investigated with clinical, colposcopic, and histologic examination as diagnostic procedures. The human papillomavirus types were also evaluated with filter in situ hybridization. One hundred one patients, 66 female and 35 male, with genital condyloma underwent an oral cavity examination. Ninety-nine (99%) practiced orogenital sex, and all were asymptomatic for oral lesions. Ninety-one underwent biopsy; histologic studies gave a diagnosis of condyloma in 48% of 101 specimens collected. In 8 of 91 (9%) oral lesions were suspected by naked-eye examination; they were confirmed histologically in all eight. Of 83 patients suspected of having oral condyloma on colposcopic examination, 38 (46%) were confirmed histologically. Thus 38 of 46 patients (83%) had oral condyloma not visible to the naked eye. Colposcopically, oral lesions appeared filiform (50%), moruloid (26%), and mixed (24%). Twenty cytologic oral samples were also collected for deoxyribonucleic filter in situ hybridization analysis. Human papillomavirus deoxyribonucleic genital types were observed in 45% (9/20) of all oral scrapings collected, and all were histologically confirmed. Our data indicate that genital human papillomavirus types are capable of establishing a local infection in the oral cavity and demonstrate a high incidence of human papillomavirus oral lesions in patients with genital condyloma.