The effect of a 21-day oral contraceptive containing 75 mu g gestodene/20 mu g ethinylestradiol on cycle control has been assessed in five clinical studies, resulting in a total of over 37 000 cycles of treatment. Results from these studies demonstrate that the preparation tends to lead to more regular cycles with a shorter and less intense withdrawal bleed when compared to baseline bleeding patterns. The incidence of amenorrhea is low, affecting from 0 to 3.1% of cycles. The incidence of intermenstrual bleeding is also relatively low and similar to the published incidence for preparations containing 30 mu g ethinyl-estradiol. After six cycles of use, the incidence of spotting ranges from 1.5 to 11%, while that of breakthrough bleeding ranges from 0.8 to 5.5%. The trial preparation has a positive effect on dysmenorrhea, and completely resolved the condition in the majority of women. Based upon these studies, it is concluded that cycle control with 75 mu g gestogene/20 mu g ethinylestradiol is good and that there is no evidence that reducing the estrogen dose from 30 mu g to 20 mu g has resulted in clinically significant changes in cycle control.