Introduction: The present study was conducted with the aim of investigating the mediator role of spiritual intelligence in the relationship between ethical performance and job burnout among nurses. Methods: The present study was an analytical cross-sectional study that was conducted at Jahrom University teaching hospitals in 2017. One hundred nurses were selected randomly. Maslach Job Burnout Questionnaire was used to measure job burnout. Dehghani Ethical Performance Questionnaire for nurses was used to assess ethical performance. Qualitative and quantitative face and content validity (CVI: .89, CVR: .93, IS: 3.5) and its reliability were calculated with the help of 10 nurses and by Cronbach's alpha (0.95). Results: Multiple linear regression by Enter model revealed that the total average of ethical performance could predict the sub-group of spiritual intelligence as much as 5.7%. Ethical performance sub-groups, could predict 9.5% of the total changes in spiritual intelligence, predict 8% of the change in reliance on the inner core and predict 10.7% of the change in relation to the essence of life. The total average of ethical performance can predict and affect the changes of individual's competency as much as 4.7%. Ethical performance is able to predict 9.9% of the individual's competency changes. Spiritual intelligence nor ethical performance cannot predict job burnout changes in emotional exhaustion and. Nevertheless, they were able to predict 6% of job burnout changes in the individual's competency domain. Conclusion: Spiritual intelligence alone cannot affect job burnout, but along with other variables such as ethical performance can have a weak mediator role.