Over twenty years ago, the concept of corporate governance appeared to minimize the loss in the firm value due to the conflict of interest inherent in the separation between ownership by shareholders and control. Governance can be classified in two sets of mechanisms: internal (Board of Directors, Ownership Structure, Executive Compensation, etc.) and external mechanisms (Mergers and Acquisitions Market, Legal/Regulatory System, etc.). The adoption of these practices is a recent trend in Brazil. For this reason, there is no consolidated empiric literature in Brazil. In such a case, the purpose of this study is to investigate the influence of internal mechanisms of corporate governance - especially the Board of Directors and the Structure of Ownership - on the performance and the firm-value of banks in Brazil. For that, the selected sample contains 19 Brazilian banks, analyzed during the period from 1998 to 2003. The results demonstrate that the influence of internal and external mechanisms on the performance variable analyzed as well as on the measure of firm value studied is still small. However, studies suggest that because financial system is a regulated sector it is possible to obtain results different from those predicted by the theory and that, until now, were obtained in studies of non- financial firms.