The increase in the numbers of customers and the various activities carried out in the Nigerian banks are growing astronomically. This has invariably made the volume of data processed to be very large thereby making the use of manual method of processing data to result in error, low productivity, slow services, insecurity, fraud and increase in human resources overhead. Coupled with the fact that today's banking operation has become a global phenomenon. In order to alleviate the challenges of these present days' banking operation; Nigerian banks have adopted the use of information technology (IT). This research work is designed to examine the roles and impacts of information technology (IT) on Nigerian industry with a particular reference to Mainstreet Bank Limited. The procedures involved collection of data which include the use of questionnaires to gather data from both the staff of the bank and customers to know the extent to which the customers have benefited from the banks since the adoption of information technology. Other sources of data are personal interview, textbooks and websites. The data is thereafter analyzed using percentage method. Thus, information technology has