Chronic obstructive pulmonary disease (COPD) is a disease state characterized by airflow limitation that is not fully reversible. Acute exacerbation of COPD (AECOPD) with increasing symptoms like dyspnea, cough and sputum is the natural history of the disease and incurs significant burden to our health care system. In Hong Kong, COPD was the 5th leading cause of death, and accounted for at least 4% of all public hospital acute admissions in 2003. Previous studies have shown that pulmonary function and quality of life were adversely affected by frequent exacerbations. Strategies to decrease the heavy use of health care resources is urgently needed for the benefits of the patients and the society.