The bronchodilator effect of carbuterol hydrochloride, a new adrenergic agonist, was compared with that of ephedrine sulfate in 12 patients with bronchial asthma. A 2-mg dosage of carbuterol hydrochloride, three times daily, was used in comparison with a 25-mg dosage of ephedrine sulfate, three times daily. The drugs were orally administered for ten-day periods in a double-blind, randomized manner. After carbuterol therapy, the mean increases in forced expiratory volume in one second and midmaximal expiratory flow rate were significantly greater in a four-hour period than those noticed with ephedrine. A decrease in bronchodilator response to both drugs was noticed on the tenth day. No side effects were noticed with carbuterol at the aforementioned dosage. The results of our study indicate that carbuterol is a safer and more effective bronchodilator than ephedrine.