Paraffin-embedded sections of vulvar squamous-cell carcinomas and of normal vulvar tissues were examined for HPV types 6, 11, 16, 18 and 33 by the polymerase chain reaction. Overall, 19 of 62 tumours harboured HPV DNA of types 16, 18 or 33. HPV types 6 and 11 were not detected. HPV DNA was found in 61% of tumours with adjacent intraepithelial neoplasia (VIN III), and in 13% of tumours without associated VIN III. HPV DNA was not detected in any of 101 normal vulvar tissues. HPV DNA was found more often in younger women, in patients with VIN III-associated tumours, and in those with multicentric anogenital neoplasia. This points to the existence of a subset of vulvar carcinomas preceded by intraepithelial neoplasia, with HPV as a major factor in carcinogenesis. HPV also seems to be an important factor in the development of multiprimaries in these patients. The 2 groups of patients with vulvar carcinoma did not differ with regard to prognosis, as estimated by the risk of recurrence after primary surgery.