Fourty-four specimens of invasive cancers of the vulva, including 38 primary invasive squamous carcinomas, were analysed by in situ hybridisation with biotinylated HPV 6/11, 16 and 18 DNA probes. Four (9%) of the 44 carcinomas were positive for HPV DNA: three (7%) for HPV 16 DNA and one (2%) for HPV 6/11 DNA. HPV DNA was found only in squamous carcinomas. Of the 38 primary squamous carcinomas, 11% were positive (8% HPV 16, 3% HPV 6/11). The overall 5-year survival was 48.7%, 48.5% for the squamous carcinomas and 50.0% for the HPV DNA positive patients.