Catastrophic healthcare expenditure refers to out-of-pocket spending for healthcare exceeding a certain proportion of a household's income and can lead to subsequent impoverishment. The aim of this study was to investigate the proportion of South Korean households that experienced catastrophic healthcare expenditure between 2006 and 2015 using available data from the Korea Health Panel, National Survey of Tax and Benefit, and Household Income and Expenditure Survey. Frequencies and trend tests were conducted to analyze the proportion of households with catastrophic healthcare expenditure. Subgroup analysis was performed based on income level. The results of the Household Income and Expenditure Survey revealed that around 2.88% of households experienced catastrophic healthcare expenditure in 2015 and that this proportion was highest in the low income group. Results also showed a statistically significant increasing trend in the number of households with catastrophic healthcare expenditure (annual percentage change=0.92%, p-value <0.0001). Therefore, the findings infer a need to strengthen public health care financing and to particularly monitor catastrophic healthcare expenditure in the low income group.