Background & Objectives: Cigarette smoking is one the causes of disease burden accounting for annual death of 4 million around the world. The aim of current study was categorizing of students smoking based on transtheoretical model and analyzing relationships of variables studied among male Students in Isfahan Medical Sciences and Isfahan University in 2009-2010 Academic year. Methods: In this Cross-Sectional study convenience sampling method was used. Data gathering instrument was the short form questionnaire based on transtheoretical model. Data was analyzed by ANOVA test. Results: 131 people (66.2%) were in precontemplation, 30 (15.2%) in contemplation, 26 (13.1%) in preparation, 8 people (4%) in action, and 3 (1.5%) in maintenance stages. Advancing across the stages from precontemplation to maintenance, self efficacy was increased and temptation decreased (p<0.05). Although, the pros of smoking increased through the stages, however, it was not statistically significant (p>0.05). The cons of smoking behavior significantly decreased through the stages from contemplation to maintenance (p<0.05). Meanwhile, during the moving through the stages, students used more behavioral and less cognitive process. Conclusion: Majority of the subjects was in precontemplation stage and it is necessary to apply interventions based on transtheoretical model constructs in order to encourage them to cease smoking. Increasing of self-efficacy and emphasizing on the cons of smoking causes to move in later stages and smoking cessation.