Objective: The goal of this study was to evaluate the insulin resistance and glucose tolerance in hyperandrogenemic and normoandrogenemic groups of patients with polycystic ovary syndrome (PCOS). Study design: In this cross-sectional study, 17 hyperandrogenemic and 14 normoandrogenemic, age and weight-matched non-obese women with PCOS were studied. All patients had clinical hyperandrogenism and chronic anovulation with polycystic ovaries on ultrasound. Insulin resistance and glucose tolerance were determined by measuring insulin and glucose concentrations following a 75 g oral glucose tolerance test (OGTT). Fasting glucose to insulin ratio (FG:I ratio), insulin area under the curve (AUC(insulin)) during OGTT. and homeostasis model assessment for insulin resistance (HOMA-IR) were calculated. Results: Hyperandrogenemic group of patients had fasting hyperinsulinemia, lower FG:I ratio, higher AUC(insulin), and HOMA-IR compared with normoandrogenemic group. The differences between two groups were statistically significant. Conclusion: PCOS has variable biochemical features. Hyperandrogenemia associated with insulin resistance differs from normoandrogenemia in this syndrome. Fasting insulin concentrations, FG:I ratio, AUC(insulin) and HOMA-IR are convenient markers for determining insulin resistance in PCOS. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.