The monophasic combination preparation containing 30 micrograms ethinyl estradiol and 75 micrograms gestodene was tested for contraceptive reliability, cycle control and tolerability in a total of seven phase III clinical studies. A total of 6,854 women were included in these studies, and 69,978 cycles were monitored. Following the commercial introduction of the preparation, further clinical data were obtained with a broader user population. In Germany it was possible to implement an extraordinarily extensive phase IV study in a very short period of time. A total of 523,477 treatment cycles in 95,906 women were included in the analysis. So, for what is probably the first time, a prospective general clinical study for an oral contraceptive was conducted of the same magnitude as the biggest cohort epidemiologic studies. The results of the various phase III and phase IV studies are in close agreement. The combination preparation containing gestodene proved to have high contraceptive reliability and gave excellent cycle control. It was well tolerated and the frequency of adverse reactions was low. To summarize, the monophasic gestodene completely fulfills the demands made of oral contraceptives today.