Abstract: Electronic banking service is growing rapidly in the world, Cooperative bank of Oromia is putting its maximum exertion to travel with technology of E- banking services. E-banking has its own effect on financial performance of the bank. This research mainly investigates the effect of E- banking on the financial performance of the Cooperative Bank of Oromia by focusing on the bank’s performance and size. For primary data collection branch staffs and managers will be interviewed while secondary data will be collected from branch documents like report of daily transactions, profit of branch and customer related data will be reviewed.