Microfinance plays an important role in the nation's financial inclusive system. Therefore, the development of Microfinance Institutions (MFIs) increasingly receives the attention of governments, especially in developing countries. In which, financial sustainability is one of the determinants which measures the development of microfinance institutions (MFIs). In this research, the institutionalist approach is applied with the purpose of developing empirical evidence for the determinants that affect the financial sustainability of MFIs in Viet Nam. Financial sustainability is analyzed through the evaluation criteria of the investors and the wholesale lending organizations. The Fixed Effect Model is applied to determine the factors that affect the financial sustainability of MFIs in Viet Nam. Quantitative results show that the financial sustainability of MFIs is governed by five factors, including (i) the growth rate of MFIs’ outstanding loans, (ii) the efficiency of MFIs’ performance, (iii) the ratio of borrowers to the number of staffs of MFIs with a positive impact; (iv) the debt-to-equity ratio of MFIs; and (v) the incremental cost per client of the MFIs with negative effec
