BACKGROUND Social support is emotional and instrumental assistance from family, friends or neighbors, and has an important but different impact on individuals, mainly depending on contextual factors. OBJECTIVE To determine the status of perceived social support and related personal and family characteristics of medical sciences students in Ahvaz, Iran. METHODS In this cross-sectional study, the target population included the students of Ahvaz Jundishapur University of Medical Sciences in the second semester of 2013-2014, of whom 763 were selected by cluster random sampling method. The study tool was a two-part questionnaire containing 48 self-administered questions including 25 questions of measurements of personal and family characteristics and a Persian modified version of Vaux's social support scale (Cronbach's α=0.745). Data were analyzed with T test, ANOVA and chi-square and using SPSS version 16 and 0.05 was considered as the level of significance. RESULTS The mean score of the perceived social support was 17.06±3.6 and 60.3% of them reported low social support. There was a significant relationship among the perceived social support and sex (p=0.02), faculty (p<0.0001), ethnicity (p=0.034) and the duration of weekly residence in dormitory (p=0.031). But no significant relationship was found between this variable and other individual and familial characteristics. CONCLUSIONS Based on students' low social support and importance of social support in reducing stress and academic failure, the planners need to provide efficient supportive interventions for students.