22 adult females with therapy-resistant acne vulgaris were treated for 12 months with Diane®1, a drug containing cyproterone acetate and ethinylestradiol. Treatment was withdrawn in 7 patients because of side-effects or lack of effect. In the remaining 15 patients, the treatment had extremely promising results, from 70 to 90% improvement of the acne. In a remarkably high number of patients, the androgen production, measured by the urinary excretion of fractional 17-ketosteroids, was elevated. None of these patients had signs of endocrinological diseases, in particular no cases of hirsutism of Stein-Leventhal syndrome were found. The current concept of the course of acne is that the conversion in the skin of testosterone to dehydrotestosterone is increased. The finding of an elevated urinary excretion of androgenic substances in this group of acne patients indicates that the pathogenesis is far more complicated.