Ventilatory function was examined in 20 elderly patients with bronchial asthma in relation to clinical asthma types, and the results were compared with those of younger asthmatics. 1. Ventilatory parameters such as FEV(1.0%), % PEFR, % MMF, % V(50) and % V(25), which repressent obstructive ventilatory dysfunction, were in general lower in older asthmatics than in the youger cases. 2. The values of % V(50) and % V(25), representing ventilatory dysfunction in small airways, were significantly lower in the older subjects with type Ib and II compared to the younger cases with same types. 3. Markedly decreased values in ventilatory parameters, particularly in % MMF, % V(50) and　% V(25) were observed in both older and younger subjects with type II. The results suggest that ventilatory function decreases with aging and the decrease is related to the pathophysiological changes in the airways.