Understanding the magnitude of the economic impact of an illness on society is fundamental to planning and implementing relevant policies. South Korea operates a compulsory universal health insurance system providing favorable conditions for evaluating the nationwide economic burden of illnesses. The aim of this study was to estimate the economic costs of asthma imposed on Korean society. The Korean National Health Insurance claims database was used for determining the health care services provided to asthma patients defined as having at least one inpatient or outpatient claim(s) with a primary diagnosis of asthma in 2008. Both direct and indirect costs were included. Direct costs were those associated directly with treatment, medication, and transportation. Indirect costs were assessed in terms of the loss of productivity in asthma patients and their caregivers and consisted of morbidity cost, mortality cost, and caregivers' time cost. The estimated cost for 2,273,290 asthma patients in 2008 was $831 million, with an average per capita cost of $336. Among the cost components, outpatient and medication costs represented the largest cost burden. Although the costs for children accounted for the largest proportion of the total cost, the per capita cost was highest among patients ≥50 years old. The economic burden of asthma in Korea is considerable. Considering that the burden will increase with the rising prevalence, implementation of effective national prevention approaches aimed at the appropriate target populations is imperative.