We analyzed the association between hyperandrogenism and hyperinsulinemia, and their relationship to body mass index, in a large series of patients with polycystic ovary syndrome (PCOS). A characteristic hormonal profile was sought in women with marked hyperinsulinemia. The patient group consisted of 73 women with PCOS, ranging in age from 16 to 29 years. The control group consisted of 34 healthy women with no evidence of hyperandrogenism, aged 1%30 years. None of the patients or control women had a body mass index above 27kg/m 2. Follicle-stimulating hormone, luteinizing hormone, prolactin, testosterone, estradiol, androstenedione, dehydroepiandrosterone sulfate, sex hormone binding globulin, 17-hydroxyprogesterone, and free cortisol were determined by radioimmunoassay. The free testosterone index was calculated. The oral glucose tolerance test was used to analyze basal insulinemia, maximum insulin peak, and the insulinemia/glycemia index. In the group with PCOS body mass index was greater, free testosterone index was higher, and levels of dehydroepiandrosterone sulfate, testosterone, 17hydroxyprogesterone (P < 0.001) and androstenedione (P < 0.05) were higher than in the control group. Of the insulin parameters, basal insulinemia, maximum insulin peak, and insulinemia/glycemia index were higher in the patient group (P < 0.001).