A multicenter trial was conducted in 267 centers in Italy to evaluate the efficacy, acceptability and safety of a monophasic oral contraceptive containing 30 micrograms ethinyl estradiol and 150 micrograms desogestrel (Marvelon) 13,290 women were followed up for a total of 74,967 cycles. No pregnancies due to method failure were reported and only three because of patient failure. Cycle control was good. There was a decrease in the occurrence of irregular cycles and in the duration and amount of menstrual bleeding; the incidence of breakthrough bleeding and spotting was low. No severe side-effects occurred and the incidence of minor complaints was generally lower during treatment than in the pre-treatment cycle. Body weight and blood pressure were not significantly altered.