Purpose: To investigate the influence of organizational justice and commitment on OCB(organizational citizenship behavior) of hospital nurses. Method: The subjects were 352 nurses who have been working in seven university hospitals. The data were collected by structured questionnaire from Feb. 12 to Mar. 5 of 2006. The data were analyzed by SPSS Win version 12.0, including descriptive statistics, t-test, ANOVA, Pearson correlation coefficient, and Stepwise multiple regression. Results: The mean score of OCB was 3.53, distributive justice was 2.74, procedural justice was 2.73, and organizational commitment was 3.28. The OCB had statistically significant differences according to age(F=8.39, p<.000), tenure duration(F=6.53, p<.000), position(F=7.65, p<.000), marital status(t=5.82, p<.000), and religion(t=3.78, p<.000). The OCB was positively correlated with distributive justice(r=.147, p=.006), procedural justice(r=.180, p=.001), and transactional commitment(r=.115, p=.032). The procedural justice(10.6%) and transactional commitment(14.3%) explained 24.9% of the variance for OCB. Conclusion: The findings showed that organizational justice and commitment were important factors for enhancing OCB in nursing organization. Therefore, the nurse manager must establish the strategies to improve the organizational justice and commitment perception of the nurses in order to promote the OCB.