In 2010, ischemic heart disease was the leading cause of disability-adjusted life-years (DALYs) worldwide. More specially, the prevalence of acute myocardial infarctions (AMI) is increasing in the aged population as mortality decreases; South Korea is no exception. This study aims to examine the economic burden of AMI in the Korean population between 2007 and 2012. AMI-related costs were assessed from a societal perspective. A prevalence-based cost-of-illness framework was used for this analysis. The subjects included all South Koreans with AMI-related ICD-10 codes (I21, I22, I23, I25.0, and I25.1). Data on direct (medical and non-medical) costs and indirect (productivity loss due to AMI-associated morbidity and mortality) costs were collected from the Korean National Health Insurance Service's claims data. The human capital approach was used to calculate indirect costs. The total estimated cost of AMI in 2012 was $1,177,649,323 USD. The majority (52%) of this amount was made up of medical costs, followed by productivity losses due to mortality and morbidity (42% of annual cost). Although the total cost declined by approximately 18% compared to 2007 ($1,427,643,854 USD), the cost of AMI in the over 60 age group amounted to 47% of the total cost of AMI in 2012. AMI led to a high economic burden in 2012. This study, which identified not only the size, but also the trends of AMI-related costs, will provide information to evaluate effects of governmental health projects and the effective allocation of public research funds.