Abstract. Microfinance institutions (MFIs) play a crucial role in the financial world and they have a double financial and social role and need to be efficient at both. There are very limited studies in the efficiency of microfinance institutions (MFIs), especially in the poor and developing countries such as Sri Lanka. Some studies which considered only financial efficiency not give attention to social efficiency. In this paper examines the social efficiency of 36 microfinance institutions (MFIs) in Sri Lanka using non-parametric data envelopment analysis using three inputs (Total Assets (TA), Operating Cost (OC) and Number of Employees (NE)) and two outputs Number of active women borrowers (WB) and Indicator of benefit to the poorest (BP). It was found that the majority of MFIs have become a considerable efficiency scores (greater than 0.5) in study year of 2013 and 2016. It can be concluded that MFIs are at the lead of the fight against poverty and provide opportunities for women in Sri Lanka.