Most studies of risk factors for human papillomavirus (HPV) DNA detection have focused on overall HPV positivity and have not examined determinants for high-risk and low-risk HPV types separately. We studied risk determinants for genital HPV infection in 1000 randomly chosen women (20-29 years) with normal cervical cytology from Copenhagen, Denmark. All women had a personal interview, a Pap smear, and cervical swabs for HPV DNA detection using a PCR technique. On the basis of their association with cervical cancer, the HPV types were categorized as belonging to a high-risk group ("oncogenic types") or a low-risk group ("nononcogenic types"). The overall HPV detection rate was 15.4%. Of HPV-positive women, 74% had oncogenic HPV types, and 30% had nononcogenic HPV types. Younger age and lifetime measures of sexual activity (notably, number of partners) were the main risk factors for the oncogenic HPV types. Furthermore, a previous Chlamydia infection was associated with the high-risk HPV types. In contrast, the most important determinants for nononcogenic HPV infection were contraceptive variables related to the physical protection of the cervix (condom or diaphragm) and number of partners in the last 4 or 12 months. Our study confirms the venereal nature of HPV infection. We hypothesize that the low-risk HPV infection, which correlates with recent sexual behavior, may be more transient than infection with the oncogenic HPV types, which correlates with lifetime exposure measurements of sexual habits.