Introduction: Learning self-regulation is a basic concept to learning, educational and cognitive psychology which has also valuable outcomes to cognitive processes and even success in life. The aim of this study was to explore the mediating role of personality styles in self-regulation and attributional styles of students of Mashhad University of Medical Sciences.Method: Present research is a descriptive-correlational study based on structural equation modeling. The statistical universe included all students of Nursing and Midwifery School from Mashhad University of Medical Sciences in the academic year of 1390-1391. Sample population consisted of 200 students who were selected through single stage cluster sampling. Then, they filled attributional style questionnaire designed by Seligman and Singh, general self-regulation questionnaire by Miller and Brown, and finally NEO five-factor personality inventory.Results: Findings of structural equation modeling showed that recommended model nearly fitted with the data of study. Furthermore, attributional style could only predcit self-regulation in the event that personality styles mediated.Conclusion: The findings of present research emphasizes indirect effectiveness of attributional styles on self-regulation of the students. Plus that personality styles can mediate between aforementioned variables.