Background and Objective: It seems that studying medicine is distinct from other academic disciplines in exerting more stress (environmental, emotional or physical), which is a unique characteristic of the medical field. This study aimed at a contrastive analysis of psychological disorders among medical and non-medical students at different educational levels. Materials and Methods: In this cause-comparison study, a total of 212 88-89 school-year medical students from Zanjan University of Medical Sciences were selected through census and evaluated by a SCL90 checklist and demographic questionnaire. Descriptive statistics (mean, and standard deviation) and inferential statistics (Kruskal-Wallis and U-Mann-Whitney) were used for data analysis. Results: After analyzing the data by the SPSS software, results show that there are significant differences in all total indexes (GSI). Particularly, the small-scale test SCL90 (except the physical preparation, anxiety, and hostility, α>0.05), shows significant differences between the three groups of medical students, P<0.01 (except for phobia, α<0.05). Interestingly, the mental health scores of the students at higher levels show a considerable improvement. Conclusion: According to the results of our study, it does not appear that studying medicine, regarding its stressful nature, has a negative impact on the mental health of the students, because the results suggest that students at higher levels exhibit even a better mental health status.