Objective · To evaluate the efficiency and safety of milk feeding to rescue failed chloral hydrate sedation in infants with cyanotic congenital  heart disease who underwent transthoracic echocardiography.  Methods · Clinical data of the infants with known cyanotic congenital heart disease were retrospectively analyzed, who were not adequately sedated after initial dose of chloral hydrate in 2015 in Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine. Vital signs and oxygen saturations were recorded every 5 minutes, and adverse events were noted. For rescue,  efficiency and safety of milk feeding were compared with phenobarbital intramuscular injection.  Results · A total of 129 infants were enrolled in this study. Fifty-two infants were rescued by intramuscular phenobarbital and the other 77 ones were rescued by milk feeding. The proportion of infants  successfully rescued by milk feeding was 55.8%, which was higher than that of intramuscular phenobarbital (30.8%, P=0.005). There was no statistical difference in incidence of adverse events between the two groups (P=0.565).  Conclusion · Milk feeding is an effective and safe choice for rescue sedation for infants with cyanotic congenital heart disease undergoing transthoracic echocardiography.