In order to clarify the relationship between human papillomavirus (HPV) and a variety of surface epithelial lesions, the presence of papillomavirus genus-specific common structural antigen (pgs-antigen) was immunohistochemically investigated in 256 cases of various tumors and tumorous lesions. The pgs-antigen was demonstrated in cases of verruca vulgaris (11/23 cases), condyloma acuminatum (13/26), adult laryngeal papilloma (3/12) and bowenoid papulosis (2/2). No pgs-antigen was observed in ordinary Bowen's disease and other hyperkeratotic skin lesions, such as keratoacanthoma and seborrheic keratosis. In uterine cervical lesions, about 15% of cervical dysplasia, most of which later developed into carcinoma in situ, contained pgs-antigen-positive koilocytotic cells. These results suggest that HPV infection is frequently present in human hyperplastic and atypical surface epithelial lesions of Japanese patients and might indicate possible association with neoplastic transformation, especially in the cervix and skin.