Human papillomaviruses (HPVs) have been associated with both benign and malignant neoplasms of the head and neck. To determine the prevalence and types of HPVs in this neoplasm, we examined fixed tissue from 21 patients by in situ hybridization. Human papillomavirus types 6b and 11 probes were used, and hybridization was positive to both types in lesions from 16 (76%) of 21 patients. Hybridization to the HPV-11 probe resulted in the most intense nuclear staining throughout the epithelium, probably indicating a high copy number. The high incidence of viral DNA sequences found in this tumor suggests a potential etiologic role. Therapeutic implications are briefly discussed.