The diagnostic and prognostic relevance of human papillomavirus (HPV) types 6, 11, 16, and 18 in squamous papilloma, inverted papilloma, and squamous carcinoma of the sinonasal epithelium was examined using the polymerase chain reaction (PCR) technique. Four (15%) of 26 squamous papillomas, 7 (24%) of 29 inverted papillomas, and 1 (4%) of 24 squamous carcinomas were positive for HPV when examined using the PCR amplification technique. Human papillomavirus 6 was present in 5 specimens (3 squamous and 2 inverted papillomas); HPV-11 was present in 6 specimens (1 squamous and 5 inverted papillomas); and HPV-18 was present in 1 of 24 squamous carcinomas. HPV-16 was not identified in any specimen. The proportion of tissue samples showing HPV presence, and the association of HPV types 6 and 11 with benign lesions and HPV-18 with malignant lesions, are both in accord with findings from prior investigations. Two major questions regarding nasal papilloma are the probability for lesion recurrence after surgical excision and the risk for malignant transformation. There is no unanimity of opinion regarding the prognostic value of histopathologic dysplasia to forecast these outcomes. HPV is etiologically related to a subset of sinonasal papillomas and squamous carcinoma, and those with benign and malignant clinical course are separable on basis of HPV type. Because of the paucity of these nasal lesions, a multi-institutional prospective collaborative study is the ideal way to address these questions.