Introduction: Professionalism is one of the soft skills which allows to be efficiently related to other, improve personal relations and lead to better work performance and fulfillment. Aim: Investigate the effect of professionalism behavior on job satisfaction of nurse managers at Assuit University hospital. Research design: A descriptive correlational design was used. Setting: This study was conducted at Assuit University Hospital. Subjects: the study subject consisted of (170) Nurse Managers classified to nursing directors, supervisors and head nurses working at Assuit University Hospital. Tools: The data collected through self – administered questionnaire which includes personal characteristics data, Behavioral inventory form for professionalism in nursing scale (BIPN) and Minnesota satisfaction questionnaire. Results: The highest mean scores regarding to professionalism behaviors domains were related to Self-regulation & autonomy, Competence and continuing education(4.59 ± 2.03), (4.21 ± 2.45) respectively. The highest mean scores regarding to job satisfaction factors were related to Communication & relationship in the work and the working conditions (23.91 ± 4.70),(19.28 ± 4.27) respectively. Conclusions: There is significant positive correlations between professionalism behavior and job satisfaction among nurse managers. Recommendations: Develop and implement continues educational programs for nurse managers that will affect the professional behavior of them.