On numerous occasions it has been suggested that Leader member exchange plays a significant role in determining organizational citizenship behavior. This study intends to investigate the effect of leader member exchange an organizational citizenship behavior among non-supervisory employees in commercial bank of Ethiopia at Bahir Dar city branches. To be able to answer the objective question of the study, the researcher used a positivist research philosophy designed with quantitative approach and cross-sectional survey design. The population of this study was professional employees of commercial banks of Ethiopia specifically Bahir Dar city branches. Using survey utilized comprehensive sampling technique, the researcher select 14 branches as target population and used proportional stratified random sampling technique to select employees. As a result, 14 branches of commercial banks of Ethiopia that found in Bahir Dar city and 219 employees in the mentioned branches were engaged in this study. Primary and secondary data were the main source of the data for the study. To undertake this study, Questionnaire distributed to 219 employees from these 203 questionnaires was return. The study used descriptive and inferential statics to analyze the collected data. Specifically, mean, correlation analysis and regression analysis were used to analyze the gathered data. The result of the study indicated that employee’s in the commercial banks of Ethiopia at Bahir Dar city branches rated their supervisor's leader member exchange while leader member exchange was perceived to be below the expected average score. The correlation result of this study confirmed that affect, loyalty, contribution and professional respect have a positive and a significant relationship with organizational citizenship behavior. Eventually, the regression analysis of the study likewise assured that leader member exchange can explain 71 % of the variation in organizational citizenship behavior. The regression analysis result reveled that there was unexplained variables in this study that need further investigation. Hence, to benefit out of the positive impact of leader member exchange, organizations must establish high quality relationship, regularly train their members on relationship issues, conduct symposiums and seminars on the benefits of high quality relationship, persuade leaders to walk the talk about leader member exchange, and create awareness on the mind of employee’s about leader member exchange and its benefit for the wellbeing of the organization.