Objective:To review a group of Australian women presenting to a reproductive endocrinologist with acne and investigate how many had androgen excess and how they had responded to endocrinological therapy.Design:All patients referred to me over a 12 month period were included in the study and investigated in a standard manner. Medical therapy was given in a non‐randomised manner based on clinical and biochemical evidence.Setting:Most patients were referred to my private practice, but all public patients seen over this period were also included.Patients:Subjects were women who presented with acne. Some were also hirsute and/or had menstrual irregularities. The total group consisted of 157 subjects. Patients with thyroid disease, hyperprolactinaemia, and late‐onset congenital adrenal hyperplasia, and menopausal women were excluded, and the final study group consisted of 90 subjects.Interventions:Women presenting with acne but no hirsutism and an elevated level of dehydroepiandrosterone sulphate were treated with low‐dose dexamethasone. All other subjects were treated with ethinyloestradiol and cyproterone acetate.Main outcome measures:(i) The diagnosis of polycystic ovary syndrome and (ii) the effect of endocrinological therapy on their acne.Results:Of the 90 subjects presenting with acne, 67 (74%) were found to have the polycystic ovary syndrome. In all cases the acne was substantially reduced by treatment. All 30 subjects who had previously failed to respond to standard dermatological preparations were successfully treated with combined ethinyioestradiol and cyproterone acetate therapy.Conclusions:The polycystic ovary syndrome is commonly found amongst women complaining of acne. Some patients will not have excess body hair, obesity or ?menstrual irregularities. Among women with resistant acne, not responding to conventional treatments, the polycystic ovary syndrome is very common. Treatment with ethinyloestradiol and cyproterone acetate is an extremely effective, safe and well tolerated therapy for these women.