Objective:To investigate the clinical effects of tracheal intubation without muscle relaxants by intravenous injection of lidocaine combined with remifentanil for laryngeal microscopic surgery.Methods:75 ASAI~II patients undergoing laryngeal microscopic surgery for tracheal intubation without muscle relaxants were randomly divided into three groups (n = 25 each) by using random number table.Group I was treated with midazolam 0.05mg.kg-1, fentanyl 2~4ug.kg-1,etomidate0.3mg.kg-1, rocuronium0.6 mg.kg-1;group II was given midazolam 0.05 mg.kg-1, fentanyl 2~4 ug.kg-1,etomidate0.3mg.kg-1,remifentanil2 ug.kg-1; group III was treated with midazolam 0.05 mg.kg-1, fentanyl 2~4 ug.kg-1,etomidate0.3 mg.kg-1, lidocaine 1 mg.kg-1 and remifentanil 1 ug.kg-1. The intubating conditions(Viby-Mogenson), extubation time and awakening quality (movement activity score of the MAAS) were recorded.Mean arterial pressure(MAP)and heart rate(HR) were also recorded before induction(T1) and immediately before(T2) and after intubation(T3).Blood sugar (Glu) and cortisol (Cor) were tested at T2 and extubation(T4).Results:There was no significant difference in the scores of Viby-Mogenson(P>0.05).MAP and HR in Group II were significantly lower than those in Group I, III at T2(P<0.05); MAP and HR at T3 were significantly higher than those at T2 in group I(P<0.05).Extubation time and MAAS score at T4 in group III were significantly shorter than those in group I,II(P<0.05). GLu and Cor in group III were significantly lower than those in group I,II at T4(P<0.05).Conclusion:Tracheal intubation without muscle relaxants by intravenous injection of lidocaine combined with remifentanil for laryngeal microscopic surgery was safe and efficient.