Introduction: More than one third of death in the world is due to unhealthy lifestyle that could be changed. Students are in the age that choosing lifestyle in that age could affect the rest of their lifetime. This study has accomplished to evaluate short-term and long-term effects of educational intervention for modifying lifestyle in students resident in Tehran University of Medical Sciences dormitories.

Materials & Methods: in this interventional quasi-experimental study, 169 girls were selected randomly to participate in group educational programs, 6 hours for each one. 2 weeks after the program, post-test, with a 9-month follow up, carried out. Data were analyzed by using of McNimar and Spearman tests.

 Results: results showed positive intervention effects on nutrition and stress management (). Also significant positive effects on physical activity were showed, but it was not significant. although 9-month after intervention results showed a decrease in the number of persons that had got to healthy lifestyle in previous stage, but tracking the changes revealed positive effects of intervention on physical activity(), nutrition(), and stress management (). There was significant positive effect on life style in short-term () and long term ().

Conclusion: life style of dormitory students improved by educational intervention; but, particularly about long term effects, it seems that these effects required to be supported in other ways.