Objective To observe preventive effects of tramadol on postoperative restlessness in children after inhalational sevoflurane.Methods Eighty children,aged 3～9 years old,undergoing selective tonsillectomy(ASA I),were randomly divided into(n=20): the preschool children(3～5 years old) tramadol group(M1 group) and the control group(D1 group);the school children(6～9 years old) tramadol group(M2 group) and the control group(D2 group).Four groups of children were induced by 8% sevoflurane + oxygen(5 L·min-1) and the equivalent dose of fentanyl.In M1 and M2 group,tramadol(2 mg·kg-1) was administered intravenously after inhalation induction.2%～3% sevoflurane + oxygen(2 L·min-1) was used to mantain the depth of anesthesia.Results There was no significant difference of operating time and extubating time among four groups.Compared with the D1 group,the restlessness incidence in recovery period in M1 group decreased slightly,but there was no statistic difference(P>0.05);Compared with the D2 group,the incidence of choking and restlessness in M2 group decreased significantly(P<0.05).Conclusion Tramadol could prevent restlessness effectively in school children receiving inhalational sevoflurane.But tramadel has no significant effect on pre-school children.