In order to investigate the relationship between the presence of human papillomavirus (HPV) DNA and cervical carcinoma, we examined the cervical screening cells as well as the biopsy specimens obtained from 3 cases of severe dysplasia, 13 cases of carcinoma in situ (CIS) and 2 cases of microinvasive carcinoma for the presence of HPV types 6, 11, 16 and 18 DNA by DNA-DNA in situ hybridization using the biotinylated HPV DNA probes. The results of in situ hybridization analysis revealed that HPV 16 DNA sequences were detected in the nuclei of koilocytosis of severe dysplasia and CIS cases. The nuclei of atypical cells obtained from cervical screening cells were positive for HPV 16 or 18 DNA sequences. Two CIS cases were positive for the presence of HPV 16 and 18 DNA sequences. None of them contained HPV 6/11 DNA sequences. Eighteen cervical screening cases were examined and 10 contained HPV 16 DNA sequences and 6 contained HPV 18 DNA sequences. We suggest that the identification of HPV DNA types in cervical screening cells by in situ hybridization might be of diagnostic and prognostic value in early cervical neoplasia.