The effect of prostaglandin E1 was studied to examine if it works favorably for peripheral circulation in pediatric patients after cardiac surgery. Dose of 0.1 mcg.kg-1.min-1 increased temperature of dorsal pedis significantly. Difference of temperature of dorsalis pedis and that of rectum was significantly smaller than that in control group. A significant increase in heart rate and a decrease in systolic arterial pressure produced no clinical side effects. We conclude that prostaglandin E1 is a useful and safe vasodilator for circulatory management of pediatric patients after cardiac surgery.