Objective:To observe the effect of induction of force-injection with midazolam on haemodynamics and serum cortisol response to tracheal intubation in elderly patients. Methods:Sixty-four ASA Ⅰor Ⅱ patients aged over 65-year-old weighing 61~74 kg undergoing selective operation under general anesthesia were randomized into 4 groups(n = 16 each) according to midazolam doses-0.01(Ⅰ),0.02(Ⅱ),0.03(Ⅲ),0(Ⅳ) mg/kg before induction of anesthesia. 5 minutes later,anesthesia was induced with midazolam(Ⅰ0.04 mg/kg,Ⅱ 0.03 mg/kg,Ⅲ 0.02 mg/kg and Ⅳ 0.05 mg/kg),fentanyl 2 -滋g/kg,etomidate 0.3 mg/kg and rocuronium 1 mg/kg. Tracheal intubation was performed at 1.5 min after rocuronium injection. BP(SBP and MAP), HR, SpO2 and RR were continuously monitored and recorded in the resting state entering room(T1,baseline),5 min after midazolam injection(T2),immediately before intubation(T3),immediately and 1,2,3,4,5 min after intubation(T4,5,6,7,8,9). Blood samples were taken from artery at T1 and T9 for determination of plasma serum cortisol concentration. Results:SBP,MAP and HR decreased significantly at T2 as compared to the baseline values at T1 in the experimental groups. Compared with those in the experimental groups,the SBP,MAP and HR and variation of SBP and HR at T4 in group Ⅳ became higher. Compared with group Ⅲ,the variation of SBP and HR decreased significantly in groupⅠ. The serum cortisol was significantly smaller in group Ⅰ,Ⅱ and Ⅲ at T9 than at baseline. But it was contrary in group Ⅳ. Conclusion:Induction of force-injection with midazolam can decrease the stress response to tracheal intubation in elderly patients effectively.