Purpose: The purpose of this study was to investigate factors related to obesity of mid-age women and to examine the relationship between obesity and chronic diseases including diabetes, hypertension, and heart disease. Methods: Using data from Korean American adults living in California, we analyzed the health behavior (diet, exercise, smoking, and binge drinking) and psychological stress of obese women with body mass index ≥25 by using chi-square test. Logistic regression was used to investigate independent effects of obesity on chronic diseases, after controlling for risk factors. Results: The prevalence of obesity appeared about 16.9%. The Obese group was less likely than the non-obese group to eat vegetables and more likely feel psychological stress. There were no significant differences in smoking, alcohol intake, and physical exercise between the two groups. Obesity was strongly related to chronic diseases (OR=4.642, 95% CI=1.328-16.222). Conclusion: This study suggests that obesity of mid-age women could be reduced by encouraging health behavior such as eating vegetables daily, performing physical exercise regularly, and taking care of emotional stress. Diet and physical activity interventions and emotional supports should be developed for weight loss and prevention of weight gain in mid-age women.