Throughout this work, we have sought to answer the following question: why are banks in deficit, is it because they are state-owned? Or because they are poorly managed? The objective of our study is to test the impact of internal governance mechanisms on the performance of Tunisian commercial banks in general and public banks in particular.The results found indicate that the problem of banks does not lie in their state ownership but in the mode of governance of these banks. We found that private banks perform better than public banks, the latter are characterized by low ratios of return on equity and assets.