Background: A person's lifestyle plays an important role in his health. This study aimed at determining thehealth-promoting lifestyle and its related factors among the medical students of Shahroud Islamic Azad University. Methods: In this cross-sectional study, a total of500 students of medical sciences were selected using the stratified random sampling method and they completed the health-promoting lifestyle, self-efficacy, and well-being questionnaires. The collected data were entered into SPSS 16 and were analyzed with a T-test, Chi-square, Pearson correlation coefficient, and a backward regression model. Results: The mean age of the students was 22.25±1.45 and 65% of the participants were female. The mean scores of health-promoting lifestyle, well-being, and self-efficacy were 134.1±23.85, 14.41±5.09, and 41.67±8.05, respectively. Among the students, 32.8% had a health disorder and only 2.2% had a high self-efficacy. Well-being and self-efficacy were statistically correlated with the health-promoting lifestyle (p<0.001). The results showed that out of 17 independent variables, only 4 variables of educational level, academic year, marital status, well-being were the best predictors of health-promoting lifestyle. Conclusion: More than 90% of students had low self-efficacy and more than 30% of them did not have good well-being. Moreover, the health-promoting lifestyle of students was moderate. More attention to the above areas, such as well-being status and applying required interventions, can help to improve the situation.