Background and Objectives: An organization requires some behavior which reflects individuals’ long-term interests for success. The behavior is termed as organizational citizenship behavior. Since organizational citizenship behavior plays an important role among Tabriz University of Medical Sciences’ academic staff, the purpose of the current study was to explore the effect of psychological capital on organizational citizenship and provide suggestions to promote the behavior within the group.

Material and Methods: This is a cross-sectional study and was carried out in 1395. The population was the academic staff of Tabriz University of Medical Sciences. The sampling process was done in cluster form and data analysis was conducted through descriptive and analytical statistic methods. In order to purify, classify and interpret the data, we used statistic descriptive methods and in the analytical level, Pearson and regression were used by SPSS software to examine the hypotheses of the study.

Results: The overall samples of the study were 300 people and the percentage of responsiveness was 85%. According to the study, average psychological capital of the academic staff in Tabriz University of Medical Sciences was 4.82 and average organizational citizenship behavior amounted to 3.75. Various dimensions of psychological capital including self-efficiency, hope, tolerance and optimism averaged 5.22, 5.19, 4.62 and 4.30, respectively. Spearman coefficient for psychological capital and organizational citizenship behavior was 0.258 (P ≤0.001).

Conclusion: According to the results of the study, the amount of changes in the citizenship behavior in academic staff amounts to eight percent through changes in the psychological capital. As a result, it can be claimed that one unit increase in psychological capital causes 0.068 unit increase in the academic staffs’ organizational citizenship behavior in Tabriz University of Medical Sciences.