This study examined the effect of performance management on organization performance in the case of ethio telecom based on a sample data collected from different work units of the organization. Out of the 334 questionnaires expected to be collected,315 are filled and collected back with no missing value. The study employed explanatory research design using multiple regression analysis. The data is analyzed using SPSS. The finding of the correlation result revealed that all the performance management practices planning, communication, reviewing, assessment and reward are positively correlated with organization performance. However, the regression result has shown that only assessment and reward significantly affects organization performance positively. Hence, the study recommends that ethio telecom need to work on its assessment and reward practices to influence its organizational performance positively and significantly