Theophylline was administered as an aerosol to nine patients with known bronchospastic disease. No significant improvement in the forced expiratory volume in one second was observed after administration of aerosolized theophylline, although improvement did occur following administration of aerosolized isoproterenol. The theoretic mechanisms of bronchodilator aerosols are discussed, as well as the possible reasons for not obtaining a response with administration of theophylline.