The frequency of human papillomavirus (HPV) type 16 in premalignant and malignant lesions of the cervix was investigated and compared with the detection of HPV type 6. In cervical intraepithelial neoplasia (CIN) grades I-III HPV 6 was detected in 28% and HPV 16 in 62% of patients whereas 90% of malignant lesions contained HPV 16 only. In the CIN lesions there was an increase in HPV 16 detection as the severity of disease increased while the level of detection of HPV 6 decreased. Only three (18%) of the cervices that were colposcopically and histologically normal contained HPV genomes; although two of these three women had either a history of genital warts or a sexual partner with penile warts.