Purpose: The purpose of this study was to analyze the factors affecting Self Care Behavior in Korean high school students. Method: Data were collected from November 9 to December 28, 2003. The participants in this study were 293 students(134 boys, 159 girls), recruited from two High School located in Seoul. Data collection was conducted through the use of Questionnaire that was modified by the investigator. The data were analyzed with descriptive statistics, Pearson Correlation coefficients and stepwise multiple regression. The SPSS win 10.0 program was used. Results: The mean of total item score the Self Care Behaviors scales was 3.37, which was slightly low. There was a significant correlation between Self Care Behavior, Hope, Social Support, and Self Care Agency(γ= .30 ～ .65, p<.001). Stepwise multiple regression analysis showed that Self Care Agency was a predictor of Self Care Behavior and accounted for 28% of the variance. Self Care Agency account for 31% of the variance in Self Care Behavior in the high school girls. Self Care Agency and Hope accounted for 27% of the variance in Self Care Behavior in High school boys. Conclusion: Self Care Agency accounted for variance in Self Care Behavior in these high school students. Therefore it is necessary to develop nursing interventions to increase Self Care Agency in high school students in order to increase the Self Care Behavior.