In a randomized study, we have evaluated the treatment of cervical human papillomavirus (HPV) lesions by CO2 laser vaporization. Fifty patients with abnormal Papanicolaou smears and histological evidence of cervical HPV infection associated or not with cervical intraepithelial neoplasia (CIN) grade I were randomized to either a treatment or a control group. The cervical swabs were obtained every 3 months in both groups and examined for HPV type 16 DNA by the polymerase chain reaction. After a follow-up period of 12 months no significant differences were found between the laser treatment and the control groups in relation to the disappearance of the abnormal Papanicolaou smear. Two patients in the treatment group and 3 in the control group had a conization because of development of CIN I or aggravation of the concomitant CIN found at the initial visit. The percentage of women who demonstrated HPV in their cervical smears at 12 months' follow-up was identical in the two groups, supporting the hypothesis that HPV is a persistent infection during which the virus is widespread in the vaginal epithelium.