To evaluate the efficacy of traraadol for the prevention and treatment of shivering after intracranial surgery performed under induced hypothermia. Methods Ninety patients ( 47 male,43 female ) ,aged 17-59 yr undergoing intracranial surgery under general anesthesia were studied. Anesthesia was maintained with isoflurane inhalation supplemented with lidocaine intravenous infusion. Esophageal temperature, HR, NIBP, SpO2 and PUT CO2 were monitored and recorded every 5 min during operation. Mild hypothermia was induced after induction of anesthesia using temperature adjusting water blanket. Esophageal temperature was maintained at 34℃-35℃ during operation. No measures were taken for rewarming at the end of operation. The patients were randomly divided into 3 groups of 30 patients in each group. In group A tramadol 200mg was given iv when the skin was being sutured, during the postoperative period if shivering occurred tramadol 50mg was given iv. Tramadol 50mg (group B) or 100mg (group C) was given iv when shivering occurred after operation. If shivering did not disappear or recurred, another 50mg of tramadol was given iv. Shivering was divided into 4 grades from 0( no shivering ) to Ⅲ ( muscles of all four extremities twitch ). Results The demographic data and esophageal temperature were comparable among the three groups. The incidence of shivering was much lower in group A ( 33.3 % ) than that in group B ( 73.3% ) and group C (76.7% ). The total dose of tramadol was the smallest and the incidence of side effects was the lowest in group A among the 3 groups. Conclusions Tramadol administrated at the end of surgery can effectively reduce the incidence of shivering during the postoperative period and causes less side effects.