Pathophysiological changes by aging were examined in asthmatics in the elderly. 1 . A level of serum IgE and frequency of positive RAST score for allergens were in general low. However, the frequency of patients with family history of allergic diseases was considerably high, and in these patients with family history having allergic diseases the presence of IgE-mediated allergic reaction was frequently observed. 2 . Bronchial hyperresponsiveness tended to decrease with aging. 3 . Ventilatory function and gas exchange (DLco) showed a decrease with aging, and the decrease in ventilatory function and DLco in older patients over age 70 was significantly lower than the decrease in younger patients with asthma under age 49. 4 . The volume of the lungs, evaluated by % residual volume (% RV) , tended to increase with aging. The low attenuation area (LAA) of the lungs < -950 HU on HRCT, which represents hyperinflation in asthma, was also increased with aging. A significant correlation was found between % RV and % LAA of the lungs <-950HU on HRCT in patients over age 70.