The purpose of this study was to investigate nutritional risk factors, perceptions on nutrition and health, nutritional knowledge, flood habits and their correlation to supplement use in middle-aged and elderly Koreans. A nationwide survey was conducted in the metropolitan areas (6 cities) and middle-sized cities (8 cities) of Korea from October to December, 2000. Subjects were randomly selected based on population, and 2,188 non-institutionalized adults aged over 50, and elderly (male 765, female 1,423) were studied. Data were collected using a standardized questionnaire administered in personal interviews. Nutrition and health-related scores of nutritional risk factors, perceptions on nutrition and health, nutritional knowledge, and flood habits were significantly higher in supplement users as compared to non-users. There was a negative correlation between nutritional risk factors and other nutrition and health-related scores on perceptions on nutrition and health, nutritional knowledge, flood habits, and pocket money. Also there was a positive correlation between nutritional risk factors and age. Therefore, these results may provide basic information for proper supplement use by middle-aged and elderly koreans.