Abstract: ObjectiveTo examine the prevalence of depression and to explore mediating role of Big Five personality on the relationship between perceived stress and depression among seven-year program medical students,and to provide evidences for promoting development of medical students.MethodsWith stratified cluster sampling,823 students in China Medical University and Dalian Medical University were selected for a cross-sectional self-administrated questionnaire survey in June 2014.A self-designed general questionnaire,Center for Epidemiological Studies Depression Scale(CES-D),Big-Five Factor Inventory,and Perceived Stress Scale were applied in the survey.ResultsAmong the participants,the average CES-D scores were 18.98±9.01 for depression and 17.90±4.74 for perceived stress;the average scores of Big-Five Factor Inventory were 24.31±4.67 for extraversion,32.67±5.24 for agreeableness,23.37±4.67 for neuroticism,32.80±5.81 for openness,and 28.75±4.68 for conscientiousness,respectively.The results of multivariate hierarchical regression analysis demonstrated that perceived stress was significantly correlated positively with depression(P<0.01);extraversion,agreeableness,conscientiousness,and openness of Big-Five personality were significantly correlated reversely with depression and stress(all P<0.01);neuroticism was significantly correlated positively with depression and perceived stress(P<0.01);and perceived stress was positively associated with depression and could explain 33.1% of variance of the depression(P<0.01).The agreeableness,conscientiousness,neuroticism of Big-Five personality played a partial mediating role,in which agreeableness and conscientiousness reversely associated with depression,while neuroticism was positively correlated with depression and could explain 11.0% of variance of depression.Extraversion and openness showed no statistically significant mediating effect.ConclusionThe agreeableness,conscientiousness,neuroticism of Big-Five personality as mediate variables are predictive factors of depression among seven-year program medical students.Releasing stress and building up the appropriate personality are beneficial to mental health among the students.