Abstract:【Abstract】Objective Intubation without prior administration of muscle relaxants is a common practice in children and in adults with potential difficult airways. Tracheal intubating conditions and time to resumption of spontaneous breathing were assessed after induction of sevoflurane with different doses of propofol in adult patients. Methods In a prospective, randomized, doubleblinded design, 90 ASAI—II patients undergoing operations were randomly divided:propofol 1mg/kg,propofol 1.5mg/kg and propofol 2mg/kg. All patients were given propofol iv after inhalational induction with 8% sevoflurane. The tracheal intubating conditions and time to resumption of spontaneous breathing were evaluated. The postoperative hoarseness were assessed. Results Tracheal intubation was successful in all patients. Intubating conditions were acceptable in 15 30 (50%), 23 30(76.7%) and 30 30(100%) in those subjects given propofol 1.0, 1.5 or 2.0 mg/kg. There were no significant differences in clinically acceptable intubating conditions between those given propofol 15 and 20 mg/kg, but they had greater acceptance than group propofol 1.0 mg/kg. The time to resumption of spontaneous breathing of groups were103.6s, 134.1s and 1962s, time to resumption of spontaneous breathing of group prop20 was longer than other groups significantly(P<0.05). Patients with no hoarseness after operation in group prop20 were more than that in group prop1.0. Conclusion After induction with sevoflurane, 1.5-2 mg/kg propofol could produce satisfactory intubating conditions, but propofol 1.5 mg/kg leads to shorter time to resumption of spontaneous breathing.