The influence of cigarette smoke on pulmonary function, airflow, lung volume, and transfer factor in patients with asthma was examined in 40 subjects over the age of 70 years (20 ever-smokers and 20 never-smokers), and 20 patients with pulmonary emphysema over age 70 (all ex-smokers). The ventilatory parameters showing airflow limitation (% FEV(1) and FEV(1)%) were not significantly different between ever-smokers and never-smokers of elderly asthmatics. In contrast, % FEV(1) and FEV(1) % values were significantly lower in patients with pulmonary emphysema than in those with asthma with or without a history of smoking. The % RV value was significantly larger and % DLco value was significantly more decreased in ever-smokers compared with neversmokers of the elderly asthmatics. However, there were no significant differences in % RV and % DLco values between asthmatics with a history of smoking and patients with pulmonary emphysema. The results show that cigarette smoke inflluences % RV and % DLco, but not % FEV(1) and FEV(1) %, suggesting airflow limitation of large and moderate size airways.