Objective: To investigate the effect of pretreatment with dezocine and tropisetron to prevent injection pain of rocuronium bromide. Methods: Two hundred ASAⅠ~Ⅱgrade patients, undergoing elective surgery were divided into four groups by random digits table with 50 cases each: dezocine group (group D), tropisetron group(group T), dezocine combined with tropisetron group (group L) and control group (group C). Before induction of anesthesia, group D received dezocine 5 mg; group T received tropisetron 5 mg; group L received dezocine 5 mg and tropisetron 5 mg, group C received normal saline 6 mL. Two minutes later, general anesthesia were induced with Midazolam 2 mg and the long chain of propofol 2 mg/kg. Rocuronium 1 mg/kg were injected in 5 s when patients loss of consciousness. The injection pain of rocuronium bromide were observed and recorded. Results: Compared with group C, the injection pain of rocuronium bromide were decreased significantly in group D, group T and group L P<0.05. Compared with group L, the injection pain of rocuronium bromide were increased significantly in group T P<0.05. Conclusion: Pretreatment with dezocine 5 mg and tropisetron 5 mg is effective in reducing the injection pain of rocuronium bromide.