Background:Adolescence is a risky period with high tendency towards drug abuse. Addressing the problem of drug abuse among students is essential.Objectives:This study was carried out in 2013 with the purpose of investigating the prevalence of substance abuse among dormitory students of Shahid Beheshti University of Medical Sciences.Patients and Methods:In this descriptive analytical study, which was carried out in 2013, a total of 604 students living at dormitories of Shahid Beheshti University of Medical Sciences were selected by random sampling method. A questionnaire designed by the researcher was used to collect the data. Data were analyzed using descriptive statistics and chi-square test.Results:The prevalence of substance abuse among the students was 15.4%. With respect to the types of the drug used by students, the highest frequencies belonged to smoking 4.47% and hookah with 42.9%. Forty-eight percent of the students, who used drugs, started it for the first time when they were 18 years old or younger. About 58% of students used drugs for the first time in dormitories and parks. Students’ meetings and parties with friends were frequent occasions for substance abuse (47.5%).Conclusions:Students are considered one of the most vulnerable groups of society. The students living in dormitories are more vulnerable to drug abuse due to the lack of parental supervision and the impact of peer pressure. Therefore, localization of acceptance at Universities in order to prevent cultural mixing of students and education programs for teaching life skills to students efficiently reduce their substance abuse.