Organizations need to employ committed individuals for their survival and development as well as to achieve their short- and long-term goals. In account of this, successful organizations are those with committed managers and staff. Therefore, it is important to investigate the factors influencing organizational commitment. The aim of this study was to investigate the mediating role of psychological capital in the relationship between spiritual intelligence and organizational commitment among employees of Ardabil University of medical sciences using a correlational method (structural equation modeling). Regarding the desirable size of the sample (n=125) for structural equation modeling, 183 employees were selected using convenience sampling method. The results showed that the direct effect of spiritual intelligence on organizational commitment and the direct effect of psychological capital on organizational commitment are statistically significant. Also, the spiritual intelligence may effect organizational commitment through psychological capital as mediator (p≤ 0.01, β=0.41).