In this paper, the author uses the index analysis to explore relationships between financial performance and structure of incomes in Vietnamese commercial banks in the years 2007-2011. Research results show that financial performance of most commercial banks is mainly determined by lending services, which implies that their profits involves high degrees of risk. The paper, therefore, can suggest some measures to improve financial strength and adjust the structure of incomes for commercial banks by controlling income from lending service and developing sources of income from non-lending services.