Twenty obese PCOS women (age: 24.7±18 yr; BMI: 30±2.4 kg/m2) were consecutively admitted to the Endocrinology Unit of the Department of Molecular and Clinical Endocrinology and Oncology of the Federico II University of Naples, and were enrolled in this clinical study. The diagnosis of PCOS was made according to the diagnostic criteria for PCOS At study entry the patients were randomized in two groups of treatment, according to insulin sensitivity. OCP group, 10 patients (BMI 29.7± 1.5 kg/m2) received 30 µg ethinylestradiol plus 30 mg drospirenone 21 day/month. MET group, 10 patients (BMI 30.4± 3.1 kg/m2), received metformin 1250 mg three times daily. The duration of follow-up was 6 months. The control group consisted of 10 healthy female volunteers, who were age matched.