To evaluate the possible role of moderate hyperinsulinemia on abnormal androgen secretion, we examined 4 age and weight-matched groups of obese subjects: 2 groups of women with normal menses whose fasting insulin (IRI) levels were less than or equal to 20 microU/ml (OB-I) or greater than or equal to 40 microU/ml (OB-I) and 2 groups of women with polycystic ovaries who were similarly grouped. All subjects underwent an oral glucose tolerance test, blood sex hormone determination and multiple LH determinations. Compared to OB, OB-PCO women showed significantly higher values of LH, androgen and estrogen concentrations. OB-I and OB-II showed similar hormonal patterns. On the contrary, OB-PCO-II presented significantly (p less than 0.05) higher androstenedione concentrations (348.7 +/- 129.9 ng/dl) (m +/- SD) than OB-PCO-I women (237.0 +/- 73.7 ng/dl). These differences were evident despite similar plasma LH concentrations. In conclusion, these results suggest that insulin may be a factor amplifying LH-dependent androgen secretion in hyperandrogenized women with obesity and PCO.