Purpose: The purpose of this study was to compare Preventive Health Behaviors (PHBs) in adults in Korea and the United States and identify factors influencing PHBs. Methods: This was a secondary data analysis study using data from the 2008 Korean National Health and Nutrition Examination Survey and the 2008 USA Behavioral Risk Factor Surveillance System. The PHBs were predicted using multiple linear regression analysis. Results: 1) The total score of PHBs was significantly higher in American males (5.11) than in Korean males (4.78). There was also a significant difference between Korean females` total score (6.57) and American females`(6.75). 2) Age, marriage, monthly income, subjective health status, and cardiovascular disease were significant factors of PHBs in Korean males (p<.001). However, age, marriage, education, monthly income, health insurance, subjective health status, and cardiovascular disease were significant factors in American males (p<.001). In Korean females, only age and education were significant predictors (p<.001). However, six variables(age, marriage, education, monthly income, health insurance, and subjective health status) were significant predictors in American females (p<.001). Conclusion: There were different variables in predicting PHBs between Koreans and Americans. Each country should focus on those significant predictors to promote the PHBs for adults.