Purpose: The purpose of this study was to evaluate the effects of a mentoring program to improve the exercise and dietary habits of adolescents. Methods: A non-equivalent control group, pretest-posttest design was used. The independent variable was a mentoring program for improvement of exercise and dietary habits of adolescents, in which the mentors were nursing students and the mentees were female middle school students. The dependent variables were weekly exercise frequency, weekly exercise time, perception of exercise benefit, frequency of vegetable intake, and dietary habits. The intervention was conducted by various methods such as group education, individual approach through the mentor-mentee relationship, and multimedia approaches. Results: At follow-up, the perception of the exercise benefit was significantly greater in the intervention group than in the control group. The weekly exercise frequency and frequency of vegetable intake in the intervention group were significantly greater after the intervention than those before the intervention. Conclusion: This mentoring program is potentially of an effective health promotion program for adolescents and will enable nursing students who participate in the program as mentors to gain confidence in their professional capability.