Background & aim: organizational citizenship behaviour is one of the important socioligicil dimen sions of educatinal organizations , including universities.University staff have the ability of performing important roles in upgading the qualily of their university. The present research was carried out with the aim of finding the correlation between job motivation and organizational citizenship behaviour of the staff of Yasuj University of Medical Sciences (YUMS) . Methods: The present paper was a descriptive analytical research carried out during 2012-2013 on 260 samples among 769 cases of the staff of headquarters and vice-chancellory departments of YUMS. The data were collected using standard questionnaires: Padsacoff’s Citizenship Behavior (1999) and Habibi’s Job Motivation (1998). The data were analysed using statistical tests, piersons solidarity coefficient and multiple regression. Results: Results of the research showed that there was a significant correlation between job motivation, the dimensions of job motivation and organizational citizenship behavior (p<0.05). Dimensions of job motivation and job motivation are significantly able to predict citizenship behavior (p<0.05). Conclusion: once the staff have sufficient motivation, and a feeling of satisfaction on their jobs, they perform their duties with more precision which causes maximum efficiency.