Background and Objective: The high levels of sensitivity and job stress for nurses require a necessity of voluntary extra-role behavior known as customer oriented citizenship behavior (COCB). The aim of this research was to examine the influence of the most important factors on COCB in nurses. Materials and Methods: In this cross-sectional study, data were gathered by a questionnaire from 198 employee nurses at Imam Reza Hospital in Mashhad, Iran. In order to test the relationship, the structural equation method was used. Results: Our results were in agreement with the significant impact of procedural justice, distributive justice, job satisfaction, and organizational commitment on external representation and internal influence, as the two elements of COCB. The effect of interactional justice on internal influence and the third element of COCB, service delivery, were also approved. Conclusion: In comparison to other dimensions of organizational justice, the procedural justice has the highest impact on job satisfaction and organizational commitment and through them on COCB. Therefore, organizational policies and procedures should be devised in a way that nurses find them fair and indiscriminating.