Objective To evaluate the effect of nalmefene on remifentanil-induced cough during the induction of pediatric general anesthesia. Methods One hundred patients undergoing elective high ligation of hernia sac under general anesthesia，2~6 years old, ASA Ⅰ ~ Ⅱ level,were divided into 2 groups (n=50 each) using the random number table： nalmefene group(group N) and control group(group C)．Nalmefene 0.25ug/kg was injected intravenously at 2 mins before anesthesia inductionin group N， and theequal volume of normal saline was given instead in group C．The incidence and severity of cough in 1 min after the injection of remifentanil in two groups were observed.The vital signs of two groups were recorded before the nalmefeneinjection(T0),before remifentanil injection (T1),after 1 min of remifentanil injection(T2) and at laryngeal mask airway inserion(T3). Results The incidence of remifentanil—induced cough was 4％in group N and 36％in group C. Compared with group C， the incidence and severity of cough were significantly decreased in group N(P<0．05)．There was no significant difference in the hemodynamic variables between the two groups (P>0.05). Conclusion Nalmefene 0.25ug/kg injected before induction of pediatric anesthesia can effectively prevent remifentanil-induced cough.