Abstract: Objective:To observe the effect and security of pre-emptive analgesia with tramadol in patients undergoing anorectal surgery by total intravenous anesthesia.Methods:Sixty patients in physical status Ⅰ-Ⅱas scored by American Society of Anesthesiologists (ASA) and undergoing anorectal surgery were randomly divided into two groups.Group A were induced with fentanyl 3 μg/kg and propofol 2-3 mg/kg,and were anesthetized with continuous infusion of propofol 6-10 mg·kg^-1·h^-1.Group B received an intravenous injection of tramadol 1.5-2 mg/kg 3 min before induction,and then were induced with fentanyl 1.5 μg/kg and propofol 2-3 mg/kg with the same maintenance as group A.The visual analogue scales (VAS) and side effects such as nausea and vomiting 6 hours after operation were observed.Results:The operation was successful in both groups.Nine patients in group A and one patient in group B resorted to drugs due to SpO₂ decrease during anesthesia.The difference was significant (P<0.01).The VAS of group B was markedly lower and the effect of analgesia was better than that of group A 6 hours after operation (P<0.05-P<0.01).Conclusions:Pre-emptive analgesia with tramadol for patients undergoing anorectal surgery using total intravenous anesthesia can provide satisfactory analgesic effect and reduce the dosage of fentanyl to 1.5 μg/kg,which may decrease the influence of SpO₂ and mean arterial pressure during anesthesia.This technique has certain clinical value.