Objective To evaluate the preventive effects of dezocine on postoperative hyperalgesia in patients after remifentanil-based anesthesia.Methods One hundred ASA Ⅰ or Ⅱ patients,aged 20-64,weighing 45-65 kg,undergoing laparoscopic cholecystectomy,were randomly divided into 4 groups ( n =25 each): fentanyl group (group F),low-dose dezocine group (group D1 ),medium-dose dezocine group (group D2 ) and high-dose dezocine group (group D3 ).Anesthesia was induced with midazolam,propofol,remifentanil and cisatracurium.The patients were mechanically ventilated after tracheal intubation.Anesthesia was maintained with target-controlled infusion of remifentanil (target effect-site concentration 4 μg/L), intravenous infusion of propofol 4-6mg· kg-1· h-1 and intermittent intravenous injection of cisatracurium 0.03 mg/kg.Groups D1,D2 and D3 received intramuscular injection of dezocine 0.1,0.2,0.3 mg/kg at 30 min before the end of surgery respectively and group F received intravenous injection of fentanyl 1 μg/kg at 15 min before the end of surgery.The emergence time and extubation time were recorded.Visual analog scale(VAS),Bruggrmann comfort scale(BCS) and sedation and agitation scale (SAS) at immediately,1 h,2 h after emergence from anesthesia (T0,1,2),and the incidence of respiratory depression,nausea and vomiting and urinary retention after extubation were recorded.Results Compared with group F,the emergence time and extubation time were shortened,the incidence of respiratory depression and nausea and vomiting was decreased in groups D1,D2 and D3,VAS score was increased and BCS score was decreased at T0-2 in group D1,VAS score at T0 was increased,while VAS score at T1,2 and SAS score at T0-2 was decreased in groups D2 and D3 ( P ＜ 0.05).Compared with group D2,SAS score was decreased at T0-2,while the incidence of respiratory depression was increased in group D3 ( P ＜ 0.05 ).No patient showed urinary retention in the four groups.Conclusion Intramuscular injection of dezocine 0.2 mg/kg at 30 min before the end of surgery can reduce postoperative hyperalgesia with little side effects in patients after remifentanil-based anesthesia.