Polycystic ovary syndrome (PCOS) is characterised by anovulation, infertility and hyperandrogenism. The condition affects about 5-10% of women in the reproductive age group. Insulin resistance has proven to be a key factor in the pathogenesis of PCOS. There are several similarities between PCOS and the metabolic syndrome, and PCOS may be a risk factor for development of type 2 diabetes and cardiovascular disease. The treatment of PCOS has, so far, been focussed on treatment of the clinical signs and symptoms. Oral contraceptives have been the standard treatment. There is now a greater focus on the management of the metabolic consequences of PCOS, primarily through lifestyle intervention to achieve weight loss and increase physical activity. Metformin has proven to be effective in the management of the metabolic disturbances, anovulation and hirsutism and is now a widely accepted therapy. The thiazolidinediones (pio- and rosiglitazone), a novel class of insulin-sensitising agents, also seem to ameliorate the metabolic disturbances and clinical symptoms characterizing PCOS, but more randomised, controlled trials are needed before clinical guidelines can be determined.