This study examines the corporate governance mechanism and their impact on performance of commercial banks in Indonesia. Focusing on differences between conventional banks (CBs) and Islamic banks (IBs), this study assessed the effect of board structure (board size and board independence) and ownership concentration on the performance of the banks as measured by ROA. The study used structured review of documents, and commercial banks financial data were collected covering a period 2015 to 2016. By employing random-effect GLS technique to test the hypotheses, this paper found that board size and bank size had statistically significant positive effect on bank performance; whereas ownership concentration had statistically significant negative effect on bank performance.