Introduction: The present study was conducted to investigate the relationship of perfectionism, self-efficacy and conscientiousness with procrastination through the mediating role of stress.Method: The research design was descriptive correlational and the study population consisted of all undergraduate students of Mohaghegh-Ardabili University. From this population, 204 students (113 females, 91 males) were randomly selected by multistage cluster sampling and responded to General Procrastination Scale (GPS), Multidimensional Perfectionism Scale (MPS), Dimension of Conscientiousness Neo Inventory (NEO-FFI), General Self-efficacy Inventory (GSS), and Perceived Stress Scale (PSS). The data were analyzed using path analysis method.Results: The results indicated that socially prescribed perfectionism and stress had a direct and positive effect on procrastination whereas conscientiousness and self-efficacy had a direct and negative effect on procrastination. Also it was found that self-efficacy and conscientiousness had an indirect and negative effect on procrastination through stress. Socially prescribed perfectionism had an indirect and positive effect on procrastination through stress.Conclusion: Stress mediates the relationship of self-efficacy, conscientiousness and socially prescribed perfectionism with procrastination. Probably stress is an important determinant of procrastination behavior.