Organizational citizenship behavior becomes one of the significant factors that enhance the organizational efficiency. Organizational citizenship behavior has been defined as behaviors that an employee voluntarily engages in organization that promote the effectiveness of clearly rewarded by the organization. However organizational commitment is very beneficial for the organization because it reduces the absenteeism rate and turnover ratio and enhances the organization productivity. In all of the organization, organizational commitment exerts a positive effect on the nurses' performance. The aim was to assess the relationship between organizational citizenship behavior and organizational commitment among nurses. The descriptive correlational design was used to explore the relationship between organizational citizenship behavior and organizational commitment among nurses. Simple random sampling was used and sample size was 164. Data were collected by a self-structured questionnaire during November 2019 to December 2019 at Dhaka Medical College Hospital. Data were analyzed using SPSS version 21. The result showed that average age of the participants was 34.19 years old. There were statistically positive significant relationships between organizational citizenship behavior with organizational commitment (r = 0.82, p = 0.000), organizational citizenship behavior with working ward (F = 6.31, p = 0.000) and organizational commitment with working ward (F = 4.45, p = 0.002). Based on the results of this study, it is indicated that lack of OCB & OC among nurses' is moderate level. The findings of this study will suggest reducing organizational hazard, and developing citizenship behavior and organizational commitment that enhance high outcome in health care organizations & quality of care. So hospital should provide in-service training for nurses' and all departments are equally. Predictive study of factors related to OCB & OC is recommended for future study. How to cite this paper: Hossain, Md.M.