Background and Aim: Mental disorders are common and serious problems that can be seen all over the world, prevention of stress, anxiety and depression will have an important role in mental health of students. This study aimed to investigate the factors affecting depression, stress and anxiety of Medical Sciences of Shushtar city in 2015.
 Materials and Methods: In this cross-sectional study, 215 medical students were randomly selected in Shushtar city. A two-part questionnaire including demographic information and questionnaire (DASS-21) was used in the study. Data analysis using Spss-21 software and descriptive statistics test, T-test and ANOVA was performed.
 Results: in this study, 104 male students (48.4%) with a mean age (21.10 ± 2.24) participated, the results of this study showed that 50.2, 48.4%, and 49.3% of students had experienced different degrees of depression, stress and anxiety, respectively. A statistically significant relationship was found between variables of residence location and marital state with the levels of stress, anxiety and depression (p <0.05). It was also observed that there is a statistically significant relationship between gender and field of study with anxiety and physical activity (p <0.05).
 Conclusions: Based on the high levels of depression, anxiety and stress in dormitory students and the protective role of the students’ home environment, stress could be slightly reduced by improving the conditions of the students’ dormitories.