OBJECTIVE: To assess the impact of metformin and of two different oral contraceptives (OCs) containing cyproterone acetate and drospirenone, on serum anti-Müllerian hormone (AMH) levels, in a cohort of women with polycystic ovary syndrome (PCOS) with hyperandrogenism.DESIGN: Prospective randomised study.SETTING: Division of Endocrinology and Human Reproduction, Aristotle University of Thessaloniki.PATIENTS: Forty-five (45) women with PCOS diagnosed according to the criteria proposed in 1990 by the NIH.INTERVENTIONS: Women with PCOS were randomised into three groups, all treated for 6 months: Group A received an OC containing 35 μg ethinylestradiol plus 2 mg cyproterone acetate, Group B received an OC containing 30 μg ethinylestradiol plus 3 mg drospirenone and Group C received metformin 850 mg × 2. Main outcome measure(s). Anti-Müllerian hormone levels were measured by a specific ELISA.RESULTS: AMH was significantly decreased under treatment with 35 μg ethinylestradiol plus 2 mg cyproterone acetate (p = 0.002 at 3 months and p < 0.001 at 6 months). Treatment with 30 μg ethinylestradiol plus 3 mg drospirenone, and treatment with metformin 850 mg × 2 did not significantly affect serum AMH levels. AMH was significantly decreased under OCs treatment compared to metformin 850 mg × 2 (p = 0.005).CONCLUSION(S): AMH serum levels were significantly decreased under treatment with 35 μg ethinylestradiol plus 2 mg cyproterone acetate, due to decrease in androgens and suppression of gonadotropins.