The effects of alpha-hANP on left ventricular function were studied with a cardiac probe in ten patients with essential hypertension. Our data showed that intravenous administration of alpha-hANP significantly elevated left ventricular function. At 5 min, the elevation of EF, RCO, ER, RSV, PFR were 13.23% (P less than 0.02), 12.7 (P less than 0.02), 0.618 (P less than 0.02), 0.133 (P less than 0.05), 0.283 (P less than 0.01), respectively. At 10 min, the increase of EF, ER, were 11.07% (P less than 0.02) and 0.233 (P less than 0.01), respectively. Atriopeptin significantly reduced systolic and diastolic blood pressure from 2 min to 20 min (P less than 0.001-0.05).