Background: The present study aimed to evaluate the prevalence of substance abuse among students of selected schools of Tehran University of Medical Sciences, Iran.Methods: This was a cross-sectional study among students in five schools of Tehran University of Medical Sciences in 2014. Data collection was conducted using a questionnaire which was designed by the researcher. Questionnaires were distributed among participants selected using stratified random sampling. A total of 422 questionnaires were filled and analyzed.Findings: In total, 422 students aged 19 to 32 years participated in this study among which 233 were women (55.2%) and 187 were men (44.3%). The highest prevalence belonged to smoking (26.3%), alcohol (19.9%), and hookah (14.9%) use, respectively. The results showed that 311 participants (73.7%) had never smoked a cigarette, 111 (26.3%) had smoked at least once, and 84 students (19.9%) had consumed alcoholic drinks at least once in their lifetime. There was no meaningful difference in smoking and alcohol use in terms of students’ gender. Mother’s educational level (P = 0.006) and financial income (P = 0.049) had significant effect on alcohol consumption.Conclusion: In this study, it was found that gender differences have reduced in cigarette smoking and alcohol consumption as seen in western countries, which should be taken into consideration. The prevalence of alcohol consumption was found to be higher compared to other similar studies conducted in Iran which is significant.