We apply Data Envelopment Analysis to compare the relative efficiency of different forms of Microfinance Institutions (MFI): Banks, cooperatives, NonGovernemental Organizations (NGOs) and Non Bank Financial Institutions. We find that that MFI that operate as NGOs are more technically efficient than bank MFIs. Using the same inputs (labor, physical and financial asset), NGOs serve more clients (number of borrowers or depositors) than Bank MFIs.