Introduction: Acute exacerbation is a natural course of chronic obstructive pulmonary disease (COPD) and repeated exacerbations are associated with decline of lung function, quality of life and mortality. However, the factors related with repeated exacerbations are not well determined. We investigated the associated factors in repeated exacerbation of COPD. Methods: Hospitalized patients with acute exacerbation of COPD were enrolled for three years (2009.01.01-2011.12.31) in a university hospital, Seoul, Korea. The rates of exacerbation were estimated during observational periods in patient with AECOPD. Clinical characteristics and courses were compared between patients with repeated exacerbations and those with not. Results: A total of 475 episodes of acute exacerbation were recorded in 208 patients with COPD (aged 69.4±10.8 years, male 64.4%). 105 patients (50.5%) had repeated episodes of exacerbations as 372 cases (2-10 per patient) from January 2009 to December 2011. Repeated exacerbations are related with characteristics of subjects like intensity of smoking, use of tiotropium, lung function and in-hospital deaths. In 52 patients had frequent exacerbations (≥ 3 exacerbations within 12months during observational periods) and these subjects had a higher prevalence of bronchiectasis, never-smoker, higher use of tiotropium and systemic steroids. Conclusions: Repeated exacerbations are relatively frequent features of patients with COPD. They are related with many clinical factors of subjects and also independently associated with in-hospital mortality.