Chronic obstructive pulmonary disease (COPD) is a basically benign disease, but the prognosis is so poor that the mortality rate is similar to some malignant diseases. Depending on the disease severity, the 5-year mortality rate of patients with COPD varies from 40 to 70%. The three major causes of death have been identified as COPD itself, lung cancer, and cardiovascular disease. The following factors have been reported to be related to survival: FEV1 (especially the maximal attainable lung function), age, gender, PaO2, PaCO2, body weight, and comorbidity. There have been several large-scale randomized clinical trials to examine the prophylactic effects of inhaled anti-cholinergics and inhaled corticosteroids on the annual decline in FEV1. However, unfortunately, in all of the published studies, these drugs had no effect on the annual decline in FEV1.