Objective To compare pharmacodynamics of vecuronium administered according to body surface area and body weight during general anesthesia.Methods Forty ASA Ⅰ or Ⅱ patients,aged 18-64 yr,weighing 40-85 kg,undergoing general anesthesia,were randomly divided into 2 group ( n =20 each ).The patients received vecuronium 2× ED95 based on body weight (group W) or based on body surface area (group S).Anesthesia was induced with propofol 2 mg/kg,fentanyl 3 μg/kg and vecuronium 0.1 mg/kg ( group W) or 2.824 mg/m2 (group S).The patients was tracheal intubated and mechanically ventilated when the maximal depression of T1 was achieved.PET CO2 was maintained at 35-45 mm Hg and BIS value was maintained at 40-50.The intubation condition was evaluated using Cooper's score.The onset time,maximal depression of T1,duration of clinical action,recovery index,duration of pharmacological action and amount of vecuronium consumed were recorded.The coefficient of variation for all the indexes mentioned above was calculated.Results There was no significant difference in the coefficient of variation for intubation condition,onset time,duration of clinical action,recovery index,and duration of pharmacological action between the two groups ( P ＞ 0.05).Compared with group W,the coefficient of variation for the maximal depression of T1 and amount of vecuronium consumed were significantly decreased in group S ( P ＜ 0.05).Conclusion Vecuronium 2 × ED95 administered according to body surface area can reduce the individual variation in pharmacodynamics during general anesthesia.