Contraceptive vaginal rings (CVR) releasing levonorgestrel and estradiol were used for contraceptive purposes in eight women. They were instructed to remove the CVR for five days only, in the case of bleeding. Three selected subjects were followed by plasma sampling during the first 60 days of treatment. Plasma concentrations of levonorgestrel, progesterone, estradiol and gonadotropins were determined. All subjects kept bleeding records and were controlled clinically in the course of treatment. The subjects were protected an average of 163 days by the CVR. Three subjects used the CVR 170--180 days without removing it and two subjects had to remove the CVR only once. Two subjects experienced quite regular bleedings, and metrorrhagic bleeding was present in one case. No pregnancies were observed during the follow-up period of 1304 days. Clinical examination revealed no pathological findings. The vaginal mucosa tolerated the treatment well. Out of those subjects who were followed by plasma sampling, pituitary suppression was more marked in the subject with continuous use of CVR.