COPD exacerbation rates vary from study to study (7-9). For example, a study conducted in Latin America reported that the rate of exacerbations per year increased with disease severity from 0.13 exacerbations in Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 to 0.87 in GOLD 2, 2.43 in GOLD 3 and 6.87 in GOLD 4. This is supported by another study which suggested that patients who have experienced more exacerbations will tend to likewise experience more frequent exacerbations in the future (10). The aim of this study was to investigate epidemiological data on COPD in South Korea to analyze the occurrence of COPD exacerbations and the risk factors associated with COPD exacerbations.