South Korea has been undergoing significant change in its population structure over the past three decades. Within 10 years, South Korean baby‐boomers will reach the age of 65 years and accelerate this change. This trend in population structure is crucial, because an aging population may increase medical demand, especially that for long‐term care (LTC) services, which would create a financial burden on society. This study estimates total LTC expenditure in South Korea from 2015 to 2050 by modifying the method proposed by the UK Personal Social Science Research Unit, the seminal study on projecting costs of LTC services. Using population data from the projections of the Korean Statistical Information Service, I stratify the projected population by gender and age, using the groups 65–69, 70–74, 75–79 and 80 or over and divide LTC services into two categories, namely facility and home care. South Korea's total LTC expenditure is predicted to continuously increase and then reach 4.2% of GDP in 2050. Expenditure on LTC services for women is higher than that for men. Moreover, the increase in total expenditure is dramatic after 2040 for home‐based services but is constant for facility services. This study shows that the presence of baby‐boomers heavily influences LTC expenditure in South Korea. Copyright © 2013 John Wiley & Sons, Ltd.