In recent years the hemodynamics in hypertensive subjects have become a focus of interest to many cardiologists. However, the relation of acid-base equilibrium to the regulation of hemodynamics in hypertensives has not received much attention. Some investigators have studied about the hemodynamics in respiratory acidosis and alkalosis, but none in metabolic acid-base disturbances. This study therefore was carried out to elucidate the influences of metabolic acidosis and alkalosis on the hemodynamics in normotensive and hypertensive subjects. Materials and Methods Three hundred ml of 0.01 N hydrochloric acid solution was injected intravenously in 10 normotensive and 6 hypertensive subjects to induce metabolic acidosis and one hundred and fifty ml of 7 per cent sodium bicarbonate solution was injected intravenously in 7 normotensive and S hypertensive subjects to induce metabolic alkalosis. Pulse rate and blood pressure were measured before and every 5 minutes after the infusion of acidotic and alkalotic solution, for 45 minutes in the former and 30 minutes in the latter. Arterial pH, plasma volume, cardiac output, stroke volume and total peripheral resistance were measured before and after the infusion. Results Changes in metabolic acidosis : Arterial blood pH fell after the intravenous infusion of 0.01 N hydrochloric acid solution. Pulse rate showed a slight fall both in normotensive and hypertensive subjects, but to an insignificant extent. Systolic, diastolic and mean blood pressures indicated no significant changes after the in-fusion in normotensive and hypertensive subjects. Extracellular plasma volume did not show any changes in both groups. Cardiac output showed a slight increase in both groups after the infusion. Total peripheral resistance indicated no significant elevation after the infusion in normotensive subjects, while it showed a moderate increase in hypertensive ones, but the difference between both groups were not significant.