The usefulness of a nondepolarizing muscle relaxant for endotracheal intubation is limited by its relatively slow onset of neuromuscular block compared to that achieved with succinylcholine. Several attempts have been made to produce a more rapid onset of muscle relaxation for endotracheal intubation. A large dose of nondepoarizing muscle relaxant may produce rapid onset but cauae undesirable side effects and a prolonged duration of neuromuscular block. The authors observed the degree of vocal cord relaxation and intubation condition 2 minutes after administration of atracurium and measured changes in mean arterial blood pressure and heart rate at the time of arrival in the operating room, just before abministration of atracurium, 2minutes after administration, and 5mins after intubation. The 40 of patients in this observation were divided into four groups. Group 1; 10patients, received 0.3 mg/kg of atracurium Group 2; 10patients, received 0.4 mg/kg of atracurium Group 3; 10patients, received 0.5 mg/kg of atracurium Group 4; 10patients, received 0.6 mg/kg of atracurium The results were as follows; 1) There were better intubating conditions in Group 3 and 4 than in Group 1 and 2(p<0.001). 2) Mean arterial blood pressure and heart rate did not change significantly after administration of atracurium in all four groups. From the above results we conclude that 0.5~0.6 mg/kg of atracurium provides satisfactory intubation condition 2 minutes after administration without hemodynamic changes.