The purpose of this research was to determine the factors that affect effectiveness of internal control systems in commercial banks in Vietnam. Through the method of qualitative research and quantitative based on reliability Cronbach's Alpha, exploratory factor analysis (EFA) and multiple regression analysis (MRA). According to the report of COSO, BASEL organizations and the other authors, control environment; risk assessment; information and communication; control activities and monitoring could affected the effectiveness of internal control systems in commercial banks. In addition, this research has indicated that there are two new factors have an impact on the effectiveness of internal control systems in commercial banks in Vietnam: political institutions and interest groups.