Our understanding of Polycystic Ovary Syndrome (PCOS) has been hampered by varying diagnostic criteria, and ignorance of the etiology of the syndrome. PCOS women are uniquely insulin resistant and obesity aggravates this underlying predisposition to insulin resistance. Diagnostic criteria which focus on hyperandrogenism and/or menstrual irregularity are more likely to identify insulin resistant women, than such criteria as abnormal gonadotropin secretion or ovarian morphology. The lack of a clear etiologic mechanism to the syndrome has led to a multitude of symptom-oriented treatments with few therapies improving all aspects of the endocrine syndrome of PCOS. Improving insulin sensitivity has become established as a baseline treatment strategy in PCOS. There are, however, few randomized controlled trials of adequate power to provide an evidence based guide to treatment in PCOS.