Polycystic ovary syndrome (PCOS) is a common and heterogeneous disorder of women in reproductive age. It is characterized by hyperandrogenism and chronic anovulation. Several studies in diverse populations estimate it's prevalence at 5-10%. Women present, in a high percentage of cases, with obesity, hirsutism, acne, menstrual irregularities and infertility. Although the exact physiopathology of PCOS remains unknown, several studies tend to point to insulinoresistance (IR) as the cause of the syndrome. IR is present in 60 to 70% of patients independently of obesity. Compensatory hyperinsulinism has a pivotal role in the physiopathogenesis of PCOS. In vitro, insulin stimulates androgen synthesis in thecal cells and decrease sex hormone-binding globulin synthesis in the liver, increasing free androgen availability.