Ten patients 55 years and older, known to have chronic obstructive airway disease with reversible component and who had required daily sympathomimetics for many years, were studied. At a clinically stable state in a sitting position, spirometry, ventilation, gas exchange, diffusion and arterial blood gas determinations were performed before and 10, 30, 60 and 120 minutes after administration of 0.5 mg of terbutaline sulfate by inhalation. Although changes were small, significant improvement in FEV1 remained even two hours after inhaling terbutaline. Increase of conducting airways reflected an increase of dead space for 120 minutes. Early rise of alveolar-arterial oxygen tension (PAO2-PaO2) with decreased arterial oxygen tension was observed. This was a transient phenomenon and not severe enough to warrant immediate therapy. No significant EKG or blood pressure changes were noted throughout the study. It appears that terbutaline, an effective long acting bronchodilator, can be safely administered to older patients with bronchospasms.