To determine the prevalence of HPV 6, 11, 16, and 18 in a population without cytological or histological abnormalities, the cervical smears of women attending three clinics in Germany were screened over the past 5 years. The filter in situ hybridization method was used throughout. A total of 20,161 smears, taken from 11,667 women, were tested. When the results of only the first examination are considered, 8.8% (950/10,778) of women with normal cytology were positive for HPV DNA. If we divide the latter into age groups, 11% (852 HPV positive/7716) were below the age of 55 years and 3.2% (98 HPV positive/3062) were above this age. When the samples from patients who had undergone at least two examinations and remained cytologically negative during the 5-year period were examined (total, 2709 women), the HPV DNA positively increased to 34.7% (640/1862) for the sexually active age groups and to 9.0% (76/847) for those above 55 years of age. This study reveals that, although papillomaviral production is most pronounced in younger women, these infections are quite common in all age groups. During the period of investigation, 19 (0.65%) patients, who were diagnosed as cytologically negative at the first examination, progressed to carcinoma in situ or invasive carcinoma. Of these, 63.2% revealed a detectable HPV infection during the study period. The progression of HPV-positive women from normal cytology to CIN or cancer occurred at an annual frequency of 0.082%. With an infected lifespan of 45 years assumed, this results in a lifetime risk of 3.7%.