Introduction: Medical-Services Insurance Organization (MSIO) is one of the major financial health institutions in Iran. The obligation of the optimal use of the resources has made the evaluation of the efficiency of this organization necessary. The purpose of this study was to measure the efficiency and the ranking of all the head offices of MSIO in Iran. 

Methods: This applied cross-sectional study was descriptive in nature. The study population constituted all the 31 head offices of MSIO. To determine the efficiency through Data Envelopment Analysis, the information related to the inputs and outputs in 2009 were collected from the Office of Statistics and Information of MSIO by means of self-developed checklists. AP-DEA Model was run in EMS software to estimate the efficiency.

Results: The mean values of the three types of efficiency of the head offices of MSIO, namely technical, managerial, and criterion were 0.5093, 0.5851, and 0.8292, respectively. Considering the findings of AP-DEA model of Data Envelopment Analysis, the capacity of efficiency promotion at these head offices- using the same amount of inputs without any increase in fees- is approximately 17 percent.

Discussion: The findings indicated that AP-DEA Model could better measure the efficiency capacity of MSIO head offices compared with the basic DEA models. It was also found that those offices showing efficiency capacity less than one bear a surplus of inputs in human resources, physical space, and overhead expenses. The development of a comprehensive plan aiming at reducing these inputs can help reach the optimal efficiency.