Purpose: The purpose of this study was to investigate the risk factors related to prehypertension in Korean adults. Methods: The data were obtained from the Korean National Health and Nutrition Examination Survey 2005. The subjects of this study were 3,981 adults aged over 20 years of age. Demographic characteristics, alcohol drinking, smoking, physical activity, stress, BMI, serum lipid profiles and blood pressure were analyzed in this study. Results: Prevalence of prehypertension was 38.9% in this study. As the result of multiple logistic regression, the risk of prehypertension in male, elderly and low income persons was increased. And the risk of prehypertension was increased in the case of problem drinking, alcohol abuse, formal smoker, overweight, obesity and hyperlipidemia in triglyceride. Conclusion: To decrease prehypertension prevalence, it is necessary to detect and manage the influencing risk factors of prehypertension such as alcohol drinking, smoking, obesity, physical activity, stress and serum lipid profiles.