Androgen levels were measured before and during 12 months of treatment with cyproterone acetate (50 mg 5th to 16th day of cycle) and ethinyl oestradiol (50 micrograms 5th to 26th day of cycle) in 26 patients suffering from dysfunctional hirsutism. Patients were included in whom androgen levels after a dexamethasone suppression test fell above the range found in normal non-hirsute women on dexamethasone. Eighty percent of patients showed a substantial improvement of their Ferriman and Gallwey score after 12 months of treatment. During the treatment the mean level of testosterone was 64%, androstenedione 55%, testosterone oestradiol binding globulin 365%, apparent free testosterone 30%, dihydrotestosterone 74%, 5-androstanediol 43%, dehydroepiandrosterone 44%, 5-androstenediol 67% and dehydroepiandrosterone sulphate 74% of basal levels. From the results it is concluded that this treatment is effective both clinically and biochemically in reducing hyperandrogenism.