The effect of intravenous infusion of glucose-insulin-potassium (G1K) on the cardiovascular functions during acute hypoxia was studied and was compared with that of normal saline(NS). 14 anesthetized dogs were forced to inhale a hypoxic gas mixture. After the first ten-minute inhalation, Pao2 and total peripheral vascular resistance decreased to 29~3l% and 66-67% of the pre-in-halation levels respectively while the pulmonary arterial pressure increased 43-49%. Then a bolus injection of GIK was given to 8 dogs, and an injection of NS to 6 dogs. Hypoxic gas inhalation was continued for 20 more minutes. 5 -10 minutes after GIK injection, the mean arterial pressure, cardiac output, stroke volume, stroke work , and left ventricular pressure all significantly increased, however, no apparent changes could be observed in any of the above mentioned parameters after NS injection. This result reveals that cardiovascular functions during acute hypoxia can be rapidly, markedly but temporarily improved when a small volume of GIK is administered intravenously.