We have analyzed a number of invasive squamous cell carcinomas for the presence of human papillomavirus (HPV) DNA using dot blot and Southern blot analysis. Seven of 31 samples (23%) were positive by dot blot and/or Southern blot analysis. In contrast, six of 11 (55%) of vulvar intraepithelial neoplasias contained HPV DNA by dot blot and/or Southern blot hybridization. Less than 50% of the invasive vulvar carcinomas contained detectable HPV DNA. The average age at onset of vulvar carcinoma is higher than that for cervical carcinoma (in which HPV DNA is detected in over 80% of cases). Therefore, the role of HPV in the genesis of vulvar carcinoma may be different from the role of HPV in the genesis of cervical carcinoma.