It has been hypothesized that insulin resistance and hyperinsulinemia contribute to the development of arterial hypertension. To further investigate this relationship, we compared arterial blood pressure in controls and women with polycystic ovary syndrome (PCO), an insulin-resistant state. Fourteen PCO women and 18 normal control women of similar age, body mass index, and race were studied. Plasma glucose and insulin levels were determined in an oral glucose tolerance test. The insulin sensitivity (SI) index was determined by the minimal model method. Systolic and diastolic blood pressure were measured by 24-h ambulatory monitoring. Left ventricular mass was assessed by echocardiography. The two groups had comparable fasting glucose levels, but the 2-h postload glucose was higher in PCO (8.0 +/- 0.5 vs. 5.6 +/- 0.3 mmol/L; P less than 0.001). Compared to controls, PCO women were significantly more insulin resistant by fasting insulin, 2-h insulin concentrations, and SI (28.3 +/- 6.7 vs. 68.3 +/- 10.0 min-1/nmol.mL; P less than 0.01). Average ambulatory systolic (121 +/- 2 vs. 118 +/- 2 mm Hg) and diastolic (76 +/- 2 vs. 73 +/- 2 mm Hg) blood pressures were similar for PCO and control women. No difference was found in left ventricular mass. Therefore, despite profound insulin resistance and hyperinsulinemia, women with PCO do not have increased arterial pressure or left ventricular mass.