This study aims at examining the corporate governance mechanisms and their impact on performance of commercial banks in the absence of organized stock exchange. The study assessed the relationship between selected internal and external corporate governance mechanisms, and bank performance as measured by ROE and ROA. The study used structured review of documents, and commercial banks financial data were collected covering a period 2005 to 2011. The findings indicated that board size and existence of audit committee in the board had statistically significant negative effect on bank performance; whereas bank size had statistically significant positive effect on bank performance. Similarly, capital adequacy ratio, as a measure of external corporate governance mechanism, had statistically significant positive effect on bank performance. In addition, absence of organized stock exchange; high government intervention; lack of corporate governance awareness, absence of national standards of corporate governance, as well as accounting and auditing; and weak legal framework to protect minority shareholder rights are the major factors with adverse impact on corporate governance and bank performance in Ethiopia.