The prevalence of some sexually transmitted viruses, possibly involved in cervical carcinogenesis, was studied in the cervix of women with normal cytology. The presence of human papillomaviruses (HPV) type 16 and 18, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) genomes in cervical cells taken from 143 healthy Italian women was investigated using the polymerase chain reaction (PCR). The study population was divided into four groups with respect to age as follows: group I, 17 to 25 years, n = 48 women; group II, 26 to 35 years, n = 30; group III, 36 to 50 years, n = 32; and group IV, 51 to 70 years, n = 33. In the first age group prevalence rates of HPV 16, CMV and EBV infection of 23%, 21% and 19% were found respectively. The infection rates of HPV 16 and CMV were shown to decrease with age, with prevalences of HPV 16 at 10% in the second group, 6% in the third and 3% in the fourth and of CMV at 13% in the second and third and 6% in the fourth groups. The prevalence of EBV infection did not decrease with increasing age (19% in the first and third groups, 20% in the second and 18% in the fourth). The occurrence of HPV 18 genome was very low (0-3%) and independent of age. In the first age group a higher percentage of double infections (16.6%) was found than in the three other age groups (6% in the second and third and 3% in the fourth). The finding of multiple infections in younger women requires further study in order to clarify the implications of such viral infections in healthy women and their contribution to the development of genital tract malignancies.