Introduction: Today, commitment nurses in health care organizations are a vital element that they would be effect on patients. So, nursing shortage might be has negative effect on quality of care. For this reason assessing factors that effect on nurses commitment  and on quality of care are important.
Aim: Assessing the relationship between organizational support, trust and organizational commitment in nurses who work in Kermanshah hospitals in 2017.
Material & Methods: This study was descriptive that 214 nurses selected randomly based on Morgan's table. For Data gathering were used these questioners; Eisenberger & et., al (1986) for organizational support, Alen & Meyer (1990) and Kanawattanachaii & Yoo for organizational trust. Their reliability by Alpha Chronbach were 0.88, 0.82 and 0.79  representatively. For analyzing Structural Equation Modeling was used.
Results: Analyzing data showed that there was significant relationship between organizational support and trust with organizational commitment. General effect organizational support on commitment was 0.89.
Conclusion: It is recommanded to nurse managers and hospital administrators use strategies for staff support that it would be help their trust and commitment to organization.