The outcome of the study is based on both the primary and secondary data and information. The primary data were collected from a total number of 50 customers (25 big and 25 mid level customers) from 10 Private Commercial Banks (PCBs). Again, total number of 50 bankers taking 5 from each sample banks was also selected as the respondents. Both the banks and customers were selected using random sampling for easy and smooth collection of data and information. Two sets of structured questionnaire keeping in line with the objectives were prepared for collecting the requisite data. The main research issues covered in the study are: adoption of online banking facilities in Bangladesh, identifying major components of online banking and their applications, knowing the main online banking services offered by the selected banks, assessing customer satisfaction on online banking service, and identifying the major problems of online banking service in selected banks. The main findings of the study are: i) it is observed that OBS has been introduced in Bangladesh in 1998. Up to December, 2010 OBS has in operation in total number of 47 banks out of 56 banks. It is reported that fully OBS has been in operation in almost all foreign commercial banks. In all the 2 nd and 3 rd generation banks of local commercial banks OBS has been in full operation. In case of all 1 st generation banks and some 2 nd generation banks have introduced partial OBS.(ii) in most of the selected banks the components namely debit card, credit card, automated teller machine such as Master Card, Visa Card, Q-cash Card, Point of sales, on line service, internet Banking and society for worldwide interbank financial telecommunication etc. have been introduced up to December 2010. (iii) the major online banking services are offered have been: View statements and account balances, Fund transfers, Bill payment, Manage savings and current account, Card service, Order cheque and books request, Stopping cheque, Fixed deposit placement and Requesting the bank statement. iv) on the basis of five point Likert scale, it is found that 60% of the customers have been highly satisfied, 24% of the customers have been satisfied and the remaining 16% of the customers have been unsatisfied on the online banking services offered by selected banks. As regard the impact of OBS on the customers, the study reveals that OBS reduces the frequency of customers’ physical visits to the banks, customers are getting substantial benefits, customers are secured and customers access to accounts round the clock etc. v) the selected customers have identified some major problems of OBS such as unavailability of a backbone network connecting the whole country, inadequacy of reliable and secured information infrastructure especially in telecommunication infrastructure; sluggish ICT penetration in banking sector; insufficient legal and regulatory support for adopting e-banking; negative attitudes of management; lack of IT resources; lack of knowledge among employees and customers etc. In order to streamline the OBS in the selected banks some recommendations may be put forward which are: i) more investments are required by the banks in upgrading and improving the quality of their service; ii) the service providers must be more responsive on security issues; iii) the government should step-in to enforce laws on protecting customer rights. The information generated in the study and its findings may be useful to the researchers, academicians, bankers and policy makers. The academicians interested for further research in this demanding area of the banks may get the findings useful. Again, bankers may also come across the findings of the study while performing their banking jobs for the full satisfaction of the customers. Lastly, the government and policy makers may also find the outcomes of the study while formulating any policy as regards OBS.