Polycystic ovary syndrome (PCOS) is a diagnosis made between late adolescence and the menopause in 5-10% of women. PCOS is a heterogeneous disorder of unknown etiology characterized by hyperandrogenic chronic anovulation. This syndrome consists of a diverse constellation of signs and symptoms, such as hirsutism, acne, acanthosis nigricans, obesity, menstrual irregularities, anovulation, and/or infertility. Features of the metabolic syndrome, including obesity, insulin resistance, and dyslipidemia, are common in this patient population. Recent insights into the pathophysiology of PCOS have shown insulin resistance and hyperinsulinemia to play a substantial role. Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Recent studies show that serum levels of inflammatory mediators, such as tumor necrosis factor-alpha and interleukin-6, are increased in the insulin-resistant conditions of obesity and PCOS. The optimal modality for long-term treatment should have positive effects on androgen synthesis, sex hormone-binding globulin production, the lipid profile, insulin sensitivity, inflammatory mediators, and clinical symptoms including acne, hirsutism, and irregular menstrual cycles. Treatment with insulin-sensitizing agents is a relatively new therapeutic strategy in women with PCOS. Current research has shown that the use of diabetes mellitus management practices aimed at reducing insulin resistance and hyperinsulinemia (such as weight reduction and the administration of oral antidiabetic drugs) can not only reverse testosterone and luteinizing hormone abnormalities and restore menstrual cycles, but can also improve glucose, insulin, proinflammatory cytokine, and lipid profiles.Clinical treatment with troglitazone, a member of the thiazolidinedione family, for the management of PCOS complications such as insulin resistance, hyperandrogenism, and anovulation was found to have beneficial effects; however, it was taken off the market over concerns of hepatotoxicity. Although troglitazone is no longer available in the US, numerous clinical trials have established the role of thiazolidinediones in the treatment of women with PCOS. Clinical data emerging regarding the utility of two of the newer, safer thiazolidinediones, pioglitazone and rosiglitazone, for this patient population, consistently demonstrate effective improvements of endocrine and ovulatory performance in women with PCOS. The benefit and importance of lifestyle modification and weight reduction, when it can be achieved, is still an important component in the long-term treatment of PCOS. Pharmacologic reduction in insulin levels using thiazolidinediones appears to offer another therapeutic modality for PCOS, which may ameliorate the progress of both hyperinsulinemia and hyperandrogenism. However, additional studies of patients so treated are necessary before these agents can be considered first-line treatment for PCOS. Convincing data from randomized controlled trials with sufficient power to detect both the benefits and risks of long-term treatment with thiazolidinediones in women with PCOS remain to be obtained.