OBJECTIVE The evidence that some women wlth the polycystlc ovary syndrome (PCOS) are hyperinsuiinaemlc has brought into question their rlsk of developing early coronary artery disease. We have focused on three cardiac risk factors which have been associated with hyperlnsulinaemla by measuring glucose tolerance, fasting serum llpld concentrations and blood pressure In women with PCOS. DESIGN Comparison of cllnlcal and biochemical measurements in lean and obese women with PCOS and in women wlth normal ovaries. Determinants of the risk factors for coronary artery disease were assessed by multiple regresslon analysis. PATIENTS One hundred and two women with ultrasound diagnosed PCOS and 19 lean women wlth normal ovaries were studled. Patients were recruited from a reproductlve endocrine cilnlc. MEASUREMENTS Fasting total cholesterol, trlglycerides, high density lipoproteins (HDL), HDL2, glucose tolerance, fasting and stimulated insulin, gonadotrophins, testosterone and androstenedlone were measured during a 2hour oral glucose tolerance test. Recumbent blood pressure was measured automatlcaliy. RESULTS Lean women wlth PCOS were found to be hyperinsulinaemlc and have reduced serum HDL and HDLz concentrations compared to women with normal ovaries; serum insulin concentrations correlated positively with plasma glucose and blood pressure measurements in multiple regression analysis. Obese women with PCOS were in addition found to have higher systollc blood pressure, serum trlglyceride and plasma glucose concentration than lean women with PCOS and controls.CONCLUSiONS These results support the evidence that hyperinsullnaemlc women wlth PCOS have an Increased rlsk of developing cardiovascular dlsease and therefore form a population in whom metabolic screenlng is advisable.