We hypothesized that the administration of troglitazone (TGZ), an insulin-sensitizing agent of the thiazolidinedione class, would improve dyslipidemia associated with insulin resistance in polycystic ovary syndrome (PCOS). Three hundred and ninety-eight women with PCOS in a multicenter, double-blind trial were randomly assigned to 44 wk of treatment with: placebo or troglitazone