OBJECTIVES: Acute coronary syndrome (ACS) is a highly prevalent disease and the third-leading cause of death in Korea, however the economic impact of ACS from societal perspective has not been investigated. This study examined the national epidemiology and economic costs of ACS in Korea for 2009. METHODS: This study used the societal cost of illness framework, consisting of epidemiology of ACS, direct medical costs, direct non-medical costs, and indirect costs such as productivity lost from morbidity and mortality of ACS. National-level health survey results and insurance claim databases were used to analyze annual health care utilization, hospitalization costs and outpatient costs of the total Korean population (48 million people). Using a data mining technique, we identified medical claims with international classification of disease 10 codes for ACS over a one year period and estimated the costs by a macro-costing method. RESULTS: Prevalence rate of ACS is estimated at 6.4 persons per 1000 population in 2009 and its mortality rate is 7.8% in 2008. During 2009, there were 309,384 patients who had at least 1 medical claim related to ACS. The total societal cost of ACS in 2009 was estimated at $1.02 billion. Direct medical cost for ACS was $380.3 million, which includes hospitalization cost of $318.8 million and outpatient cost of $61.6 million. The direct non-medical cost, involving transportation cost and caregiver cost, was estimated at $10.1 million. Indirect costs associated with morbidity and mortality of ACS were $627.2 million. CONCLUSIONS: The study showed that the societal cost of ACS in Korea is markedly high, particularly the indirect cost, followed by hospitalization cost. Early and effective management of the disease is necessary to reduce mortality and morbidity of ACS. Findings of this study suggest for further research to uncover ways to reduce the economic burden of ACS in Korea.