Tissues from 52 cervical carcinomas, 15 cervical intraepithelial neoplasias III (CINs III), and 3 vulvar carcinomas were examined for the presence of human papillomavirus (HPV) sequences by Southern blot hybridization with HPV 16 or 18 DNA as the probe. HPV 16 or 18 DNA was detected in only 17 cervical carcinomas (33%), 5 CINs III (33%), and 1 vulvar carcinoma (33%). These frequencies are lower than those reported by others. However, new, as yet unidentified, HPVs were also detected at rather high frequency under less stringent conditions of hybridization using HPV 16 and 18 DNAs as probes. These HPVs did not hybridize with HPV 6, 11, 16 or 18 under stringent conditions, and were different from two other known types of genital tumor-associated HPVs, HPV 31 and HPV 33, judging from the patterns of their restriction enzyme digests. The total frequencies of HPV sequences were 48% (25/52) for cervical carcinomas, 53% (8/15) for CINs III, and 67% (2/3) for vulvar carcinomas.