This study examines the left ventricular function (by first-pass radionuclide angiography with a multicrystal gamma camera) at rest and during symptom-limited upright exercise in 27 normal subjects (group 1), 25 normotensive subjects with exaggerated systolic blood pressure response to exercise (greater than 200 mm Hg) (group 2) and 25 patients with essential hypertension and no associated coronary artery disease (group 3). There were no significant differences between groups 1 and 2 in exercise tolerance, heart rate, total vascular resistance, left ventricular ejection fraction and end-systolic volume. However, the exercise cardiac index and systolic blood pressure were significantly higher in group 2 (P less than 0.02). Compared to group 3, the subjects in group 2 had higher exercise heart rate (P less than 0.0001), cardiac index (P less than 0.0001), systolic blood pressure (P less than 0.0001) and left ventricular ejection fraction (P less than 0.0001) and lower exercise total vascular resistance (P less than 0.0002) and end-systolic volume (P less than 0.01). Thus, the hemodynamic profile in subjects with exaggerated systolic blood pressure response to exercise differs from that of essential hypertension; it may represent a supernormal response.