The purpose of this study was to analyze the effect of psychological capital on organizational citizenship behavior through Amos software. This study is a descriptive-survey research from the population of 249 faculty members from three faculties of the University of Isfahan, from whom a sample of 98 persons were selected by cluster random sampling. The sample answered the Organizatioan Citizenship Behavior (Netemeyer et al., 1988) and Psychological Capital (Luthans et al., 2007) Questionnaires. The results of path analysis via Amos software indicated that psychological capital have a direct and significant effect on the organizational citizenship behavior (P<0.01). Also psychological capital was effective indirectly with the mediation of organizational citizenship bihavior variable on altruism, concientiousness and civic virtue (P<0.05). But, the effect of psychological capital on sportmanship in the model was not confirmed.