Thracheal mucoss needs humidification and warming of inspired gas to maintain normal ciliary movement. But general endotracheal anesthesia may impari ciliary function and increase mucous viscosity as dry anesthetic gases pass over upper airway. Acetylcysteine inhalation which destruct disulfide bond(S-S) between mucoprotein and mucopolysaccharide of mucus had been tried to overcome thick mucus. but infrequent bronchial spasm may occur during acctylcysteine inhalation especially in patients with asthema. Therefore inhalation of isoproterenol with acctylcysteine may decrease the chance of bronchial spasm. In addition to bronchodilating effect of isoproterenol, tachycardia or hypertension may also occur. We tried to evaluate the effect of Newcomix which contains 10% acetylcystein and 0.05% isoproterenol on bronchial spasm and its hemodynamic effect in eighteen ASA l or ll adult surgical patient in recovery room, and the results were compared to those of eight non-treated patient group. The results are as follows: 1) No patient revealed bronchial spasm in Newcomix inhaltion group. 2) tidal volume significantly increased after inhaltion of Newcomix in regard to insignificant increase in non-treated group, but there were no differences in arterial blood gases. 3) There were no hemodynamic changes(blood pressure and heart rate) with 0.05% isoproterenol inhaltion. With the above results we conclude that inhalation of Newcomix is safe mucolytic agent during and/or after general anesthesia.