Undernutrition could be a significant deterrent to healthy aging and could negatively affect health outcomes in elderly. This study aimed to assess health-related factors which are associated with nutritional risks in middle-aged and elderly individuals by a cross-sectional study. Interviews were conducted with 2660 subjects (847 males, 1813 females), aged 50 years and over, in 15 cities in Korea. Data on food intake were obtained through a validated semi-quantitative food frequency questionnaires. Nutritional status were analyzed according to health-related factors including cigarette smoking, alcohol drinking, exercise, stress and depression level. Less regular exercise was associated with a higher likelihood of a poor nutrition [odds ratio (OR) 1.94; 95% confidence intervals (CI) 1.43-2.65] of middle-aged and elderly male subjects. Cigarette smoking (OR 1.84; 95% CI 1.24-2.71), less exercise (OR 2.58; 95% CI 2.07-3.21), stress (OR 1.73; 95% CI 1.36-2.22), and depression (OR 1.34; 95% CI 1.08-1.67) of middle-aged and elderly female subjects was associated with a higher likelihood of a poor nutrition. The results of the multiple regression analysis showed that less exercise proved to be the strongest predictors for the poor nutrition, followed by stress, smoking, and depression (model R2= 9.0%). It suggests that guidance to promote regular exercise, to quit smoking, to minimize stress and depression level might help to improve nutritional status of middle-aged and elderly in Korea. These findings also suggest that having recommendable health behaviors are beneficial to the good nutrition of subjects aged 50 years and over.