Purpose: This study aimed to determine the levels of burnout, self-efficacy, intention to stay, and organizational citizenship behavior (OCB) among nurses in small- and medium-sized hospitals, and factors related to nurses' OCB. Methods: A targeted sampling method was adopted, whereby 185 clinical nurses employed at 1 of 4 hospitals were enrolled in the study. OCB was measured with a tool developed by Podsaoff et al. Associated factors, including nurses' general characteristics, burnout, self-efficacy, and intention to stay, were measured using a structured survey. Data were analyzed by frequencies, t-test, ANOVA, Duncan's multiple test, Pearson Correlation Coefficient and multiple stepwise regression. Results: Levels of OCB in nurses was on average 3.52 on a scale of 1 to 5, exhibiting a positive correlation with self-efficacy and intention to stay, and a negative correlation with burnout. The final related factors were self-efficacy, burnout and intention to stay with a predictive and explanatory power of 52% for OCB. Conclusion: To increase the level of OCB of nurses, an environment in which such behavior is encouraged needs to be established by introducing measures related to administrative support and task efficiency that reduces mental burnout, while increasing self-efficacy and intention to stay.