OBJECTIVE: To investigate the effect of diet, physical exercise and sibutramine administration on serum anti-Müllerian hormone (AMH) levels, hormonal and metabolic parameters in overweight and obese patients with polycystic ovary syndrome (PCOS).STUDY DESIGN: Prospective clinical study, in an outpatient clinic setting, of 76 overweight and obese women with PCOS. All patients were placed on a hypocaloric diet, physical exercise plus sibutramine (10 mg per day) for the first month and then on either a hypocaloric diet, physical exercise plus sibutramine (10 mg per day) or a hypocaloric diet and physical exercise for the subsequent 6 months. Serum AMH levels, body composition, hormonal and metabolic features and insulin sensitivity indices were evaluated at baseline and at 4 and 7 months of treatment.RESULTS: Body weight reduction was greater in the sibutramine group. Moreover, serum FSH and testosterone levels decreased, and SHBG, free androgen index and all indices of insulin resistance significantly improved at 4 and 7 months. Serum AMH levels decreased only in PCOS women who received sibutramine, at both 4 and 7 months of treatment.CONCLUSION: A hypocaloric diet and a diet plus sibutramine both resulted in significant weight loss in overweight and obese women with PCOS. Patients who received sibutramine showed greater weight loss and improvement in hyperandrogenemia and insulin sensitivity after 7 months of treatment. Serum AMH levels significantly decreased at both 4 and 7 months of treatment only in PCOS women who received sibutramine, indicating a possible direct, gonadotropin independent effect of sibutramine on the ovarian production of AMH.