Prior studies investigating the relation between the financial performance and corporate governance mechanisms for firms in Tehran Stock Exchange mainly exclude banks due to their different types of rules and structure. We study the relation between corporate governance structure and financial performance of the banks under the non-usury banking act. We study various corporate governance factors including board size and the number of non-executive board members using a sample of 21 banks for 2010 to 2012. Result show a significant positive correlation among board size and financial performance. However, non-executive board members do not correlate with financial performance.