Bronchodilator efficacy of oral administration of aminophylline (400 mg) and terbutaline sulfate (5 mg) was compared with inhalation of three puffs of albuterol sulfate in 17 patients with stable chronic obstructive pulmonary disease in a double-blind crossover study. Two hours after either form of therapy, the patients were treated again with three puffs of albuterol. Forced expiratory volume in one second (FEV₁) increased significantly more from the baseline value after albuterol aerosol than after oral medication at 30, 60, and 120 minutes (paired t test, p < 0.01). After three puffs of albuterol at 120 minutes, FEV₁ increased to similar values an hour later on both days in 14 of 17 patients. Thirteen patients complained of side effects during oral therapy and none during aerosol therapy. Maximum bronchodilatation was achieved by albuterol aerosol in 14 of 17 patients, and addition of oral therapy produced no further increase of flow rate in these patients. Bronchodilator aerosol is the logical choice for treatment of chronic obstructive pulmonary disease because it is more effective than oral therapy and because it is free from side effects.