Purpose: The purpose of this study was to investigate the factors influencing health promoting lifestyle in high school students. Method: The study subjects were 477 high school students. The data were analyzed by descriptive statistics, t-test, ANOVA, Scheffe test, Pearson correlation and Stepwise Multiple Regression with SPSS statistical program. Results: The average item score for health promoting lifestyle was 2.44. The highest subscale score was self actualization (2.85), while the lowest subscale scores were interpersonal relationship (2.82), nutrition (2.57), exercise (2.56) and health responsibility (1.77). There was a significant difference between gender, sleeping hours, perceived health state, economic state, school performance, father's education, mother's education, living together and health promoting lifestyle. The most powerful predictor of health promoting lifestyle was self-efficacy (29.9%). The combination of self-efficacy, family function, activity-related effect, commitment to a plan of action, situational influences and social support accounted for 55% of the variance in the health promoting lifestyle. Conclusion: Self-efficacy was the most powerful variance of health promoting lifestyle. Therefore, health promoting programs that increase self-efficacy should be developed to promote a healthier lifestyle among high school students.