This study analyzed the impact of credit portfolio diversification on the profitability by using the data of 20 Vietnam commercial banks from 2009 to 2015. The results from Feasible Generalized Least Squares (FGLS) estimation show that the strategy of diversifying the credit portfolio increased the profitability of commercial banks. In addition, the study also indicates that the positive correlation of the ratio of owners’ equity, credit growth, liquidity, assets, inflation rate with the profitability; while the increase in non-performing loan decreased the profitability of these commercial banks.