Although carcinoma of the uterine cervix has been shown to be strongly associated with human papillomavirus (HPV) infection, a sexually transmitted disease, similar detailed data are lacking in penile carcinoma. To determine the association of HPV with penile carcinoma, we examined 30 specimens of penile carcinoma from 23 patients by the highly sensitive polymerase chain reaction (PCR) and in situ hybridization assays. We also examined nonneoplastic penile foreskins from 20 adults using the polymerase chain reaction assay. Human papillomavirus type 16 genome was found in 15 patients (65%), HPV type 30 was found in three (13%), and HPV type 6/11 was found in two (9%). These HPV types were not detected in any of the nonneoplastic foreskins. As in cervical carcinoma, HPV, particularly type 16, is strongly associated with penile carcinoma and may play an etiologic role in the development of this neoplasm.