Objective: To examine the prevalence of food insecurity and to identify factors that contribute to it in the Republic of Korea. Design: A cross-sectional study. Setting: Data were selected from a secondary data set, the third Korean Welfare Panel Study. Household food insecurity was measured with a six-item Korean version of the US Household Food Security Survey Module. The differences in proportions or means of household characteristics, householder's characteristics, economic status and social benefits by food insecurity status were tested with the x 2 or t test. The independent associations of food insecurity with each characteristic were assessed with multivariate logistic regression analysis. Subjects: The sample size consisted of 6238 households. Results: The prevalence of food insecurity was 5?3 % among all households and 25?7 % among low-income households. Risk factors that were associated with a higher risk of food insecurity included living alone, unemployment, no job, low household income and living in a leased or rented home. For low-income households, living in a leased or rented home increased the risk of food insecurity. Among food-insecure households, 26?1 % of the full sample of households and 34?3 % of low-income households were participating in food assistance programmes. Conclusions: Food insecurity among the Korean population was related to household type, income, job status and housing. Food assistance programmes were not enough to completely alleviate food insecurity.