In a retrospective case-control study biopsy specimens of cervical intraepithelial neoplasia (CIN) lesions from 47 women in whom invasive cancer subsequently developed (cases) and from 94 control subjects in whom CIN was diagnosed within 6 months of the diagnosis for the matched case subject but invasive disease did not develop were tested for human papillomavirus (HPV) DNA with tissue in-situ hybridization. There were no significant differences in the frequency of detection of HPV DNA between the two groups. In a cross-sectional survey the prevalence of HPV DNA was found to be 11% in specimens without CIN, 27% in those with CIN I, 49% in those with CIN II and 56% in those with CIN III. The positivity rates for HPV 16/33 DNA increased with the severity of CIN, but this was not observed for HPV 6/11 and 18 DNA. A comparison of the results of the case-control and cross-sectional studies suggested that the younger cohort of women had higher prevalence rates of HPV DNA than the older cohort.