Introduction: The aim of this research was to investigate the relationship among organizational citizenship behavior (OCB), organizational commitment, and loyalty to a company. 380 employees of Saipa company were randomly selected to participate in this study.Method: The participants answered Organizational Citizenship Behavior Questionnaire 1 (Podsakoff, Mackenzie and Fetler, 1990), Organizational Citizenship Behavior Questionnaire 2 (Dyne, Graham and Dinesch, 1994), Organizational Citizenship Behavior Questionnaire (Meyer and Allen, 1990), and Propensity to Stay in Job Questionnaire (Wiener and Vardi, 1980). Stepwise regression was used to analyze data.Results: Results of the study reveal a positive correlation between affective commitment, advocacy participation, sportsmanship, and obedience. However, there was a significant negative correlation between affective commitment and altruism. Results also showed that advocacy participation, loyalty and functional participation predict continuous commitment. Normative commitment can also be predicted by advocacy participation and obedience. Another interesting findings were relation between broad dimensions of OCB and organizational commitment.Conclusion: The findings of this study can be useful when it is important to select committed and loyal personnel for a long period of time.