ABSTRACT In spite of the fact that vasopressin has been commonly used in infants suffering from vasodilatory shock occur after cardiac surgery, the effectiveness and hemodynamic effects of vasopressin have not been completely recorded. Moreover the patients with left heart abnormalities were reported in previous researches. Its use in the patients with right heart abnormalities has not been reported until now. 70 back to back patients with right heart abnormalities were examined in Fuwai Hospital from October 2013 to September 2015, to make a clear vision of hemodynamic effects of vasopressin in patients with vasodilatory shock after cardiac surgery. It was continuously administered at a dose of 0.0002 to 0.002 u/kg/min. Before and after vasopressin administration, the difference between hemodynamic, urine output and the doses of catecholamine vasopressin were estimated. After 2 hour of administration of vasopressin, there was an increased blood pressure and the systemic vascular resistance was also elevated, on the other hand the heart rate, pressure of right atria and pressure of pulmonary artery was decreased. The need of fluid and catecholamine vasopressin was decreased later and urine output was increased. After 12 h of administration of vasopressin, there was a striking reduction in the lactate concentration. All the 70 patients survived to hospital discharge. This study showed that when the vasopressin was administered in low doses in pediatric patients after cardiac surgery, it showed a considerable improvement of hemodynamic in appropriate time without causing any side effect.