In situ hybridization (ISH) for human papillomavirus (HPV)-6, -11, -16, -18, and -31 DNA was performed on 615 formalin-fixed paraffin-embedded cervical biopsies using biotinylated DNA probes. Results were obtained from 584 samples with 266 (45.5%) containing HPV-DNA sequences. Ninety percent of condyloma acuminatum specimens were positive for HPV-DNA with 18 of 19 positive cases containing HPV-6 or -11 DNA. The detection rate of HPV in cervical intraepithelial neoplasia (CIN) lesions was 50.6% (239 of 472), while only 8 of 91 (8.9%) cervical biopsies considered to be histologically normal or with minimal dysplasia contained HPV-DNA as demonstrated by ISH. The prevalence of HPV-16, -18, and/or -31 DNA increased with the severity of the lesions, with 20 of 20 (100%) positive CIN-III lesions containing these viral types compared with 102 of 157 (65.0%) positive CIN-I lesions. ISH with biotinylated DNA probes appears helpful in identifying lesions containing higher risk viral strains.