76 women with virilizing features (68 women suffering from hirsutism and 8 from acne) were treated on average for 25 months according to different models of Androcur medication. Success of treatment was clinically assessed as good in 3/4 of the cases and slight in the remaining 1/4. However, treatment is more successful in cases of adrenal hirsutism than in idiopathic hirsutism. Moreover, success of treatment seems to be better in women below 35 than over 35 years of age. Side effects, mostly bleeding anomalies and fatigue, were found in 31 women; these must be attributed to the gestagenic component of cyproterone acetate. By contrast, 12 women showed positive side effects such as weight reduction, improvement in depression states and reversal of hair loss, which must be attributed to the antiandrogenic component. The selected continuation rate in all subjects was 86% and the unselected 72%, over a treatment period of 4.5 years. Furthermore, hormonal controls were carried out under treatment. These showed, on average, a depression of plasma androstendione of 17%, of total plasma testosterone of 47%, as well as an inhibition of the testosterone/sex hormone-binding globulin quotient of 58%. These inhibition effects speak in favour of alterations taking place in steroid metabolism. However, by inhibition of androgenic serum levels, the mechanism of cyproterone acetate is only assisted, while the main mechanism is based on peripheral receptor inhibition. Furthermore, as additional component in this action a slight increase in plasma binding capacity was found during combined cyproterone-oestrogen treatment.