The prevalence of genital human papillomavirus (HPV) infection in Hungarian female populations is not essentially different from that found in other countries of Europe and North-America. Using filter in situ hybridization (FISH), we found that, in a group of cytologically normal women some low risk HPV types (such as HPV 6 and 11) and the most important high risk HPV types (HPV 16 and 18) were present in 23% and 8%, respectively. Eighty-eight percent of condyloma acuminatum patients harboured HPV 6 or HPV 11 in their tumours. On the other hand, in precancerous lesions (cervical intraepithelial neoplasia, CIN) HPV 16 was the predominant type, being present in 29-48% of patients, depending on the detection method used (Southern blot hybridization vs. polymerase chain reaction). The detection rate of high risk HPV types was found to rise with the increasing severity of cervical neoplasia. Finally, 48% of invasive cervical carcinoma specimens were positive for HPV 16 DNA in a type-specific polymerase chain reaction. For patients with HPV 16 positive primary tumours, all but one lymph node metastases and about 30% of histologically normal lymph nodes proved positive for HPV 16 DNA. Our results--in accordance with the numerous data found in literature--seem to confirm the hypothesis that certain HPV types are greatly involved in the development of cervical cancer.