One of the leading and contemporarily become prominent issue in the finance institutions is the capital structure. Islamic microfinance institutions as one of instrument to solve the poverty problem have risen to the forefront as invaluable institutions in the development process. Since capital constraints have precluded the expansion of microfinance programs and microfinance institutions have had various degrees of performance and sustainability, the question of how best to finance these organizations is a key issue. This paper attempt to explore how changes and variety source of fund in capital structure could improve Islamic microfinance institutions efficiency and financial performance.