Introduction: The faculty members' attitude toward professionalism has a significant impact on conveying professional values to learners. The aim of this study was to assess the professional attitudes of the clinical faculty members of medical school in TUMS. Methods: In this cross-sectional study, 134 clinical faculty members of Tehran University of Medical Sciences using stratified sampling from different clinical departments were participated in 2017. The research tool was a 21-item questionnaire designed to assess the physicians' attitude about professionalism which was developed and validated by experts. The data were analyzed Using Kruskal Wallis and Pearson correlation coefficient through SPSS. Results: The average score of the participants' professional attitude was 69.96 out of 100 with standard deviation of 9.5. The highest average of the positive attitude was 94.05 out of 100 for the issues of receiving commission for referral to the colleague and receiving consultation from the colleague and the lowest average of attitude was 28.57 out of 100 for the Team working collaboration of the physician and nurse, the patient's duty to participate in medical education in the academic hospital, spending enough time for listening to the patient's concerns and the doctor's right to choose his/ her patient. Professional attitude score was significantly higher in the psychiatric group in comparison with urology (p=0.046), surgery (p=0.002), Gynaecology (p<0.001) orthopedic (p=0.003) and internal medicine (p<0.001). Conclusion: According to the findings, professional attitude of faculty members is far from ideal. Their highest positive attitudes were about excellence, honesty, integrity and respect while their highest negative attitudes were regarding altruism and duty. It is suggested that re-trining programs focused on medical professionalism, continuously in transferring attitudes, with more emphasis on the principle of altruism and responsibility for the empowerment of clinical faculty members in medical schools should be considered.