Abstract: Objective:To investigate the effects of different dosages of remifentanil on dose and time in propofol target controlled infusion(TCI) induction.Methods:Forty patients,classified as ASAⅠ-Ⅱ,undergoing general anesthesia were randomly divided into four groups:group Ⅰ,group Ⅱ,group Ⅲ and group Ⅳ.Anesthesia was induced with propofol target controlled infusion,the target plasma concentration of propofol was started with 1.5 mg/L,and increased 0.5 mg/L every four minutes.When patients lose response,the patients received remifentanil infusion,the dosage was set at 0.1,0.2,and 0.4 gkg-1min-1 in group Ⅱ,group Ⅲ and group Ⅳ,respectively.The group Ⅰ as a controll received normal saline.When modified obsever is assessment of alertness/sedation scale is zero,0.6 mg/kg tracrium was given to facilitated tracheal intubation after 3 min.The infusion time of remifentanil and total dose of propofol were recorded.The adverse effects such as hypotension,bradycardia and respiratory depression were recorded during induction.Results:The propofol dosages in group Ⅰ were higher than those in group Ⅱ,group Ⅲ and group Ⅳ(P0.05-P0.01).The propofol dosages in groupⅡ were higher than those in group Ⅲ and group Ⅳ(P0.01 and P0.05);There was no significant difference between groupⅢ and group Ⅳ(P0.05).The infusion time of groupⅠ was not significant different with group Ⅱ(P0.05),but there were significant differences with group Ⅲ and group Ⅳ(P0.01).In contrast to Group Ⅱ,there were differences with group Ⅲ and group Ⅳ(P0.01);and differences between group Ⅲ and group Ⅳ(P0.05).The accidence of adverse effects had significant differences(P0.01).Conclusions:Different doses of remifentanil can reduce the infusion time of propofol TCI,reduce the dose of propofol;propofol TCI induction combined with 0.2 gkg-1min-1 remifentanil infusion can meet the clinical needs.