Background: Nowadays, restriction on access and optimum use of resources is the main challenge of development in all organizations. Therefore, the aim of this study was to determine the Technical Efficiency and its factors, influencing hospitals of Tehran.Methods: This research was a descriptive-analytical and retrospective study conducted in 2014-2015. Fifty two hospitals with public, private, and social security ownership type were selected for this study. The required data was collected by a researcher-made check list in 3 sections of background data, inputs and outputs. The data was analyzed by DEAP 1.0.2, and STATA-13 technique.Results: Seventeen (31/48) of hospitals had the Efficiency score of 1 as the highest Technical Efficiency. The highest average score of Efficiency was related to social security hospitals as 84.32, and then the public and private hospitals with the average of 84.29 and 79.64 respectively. Tobit regression results showed that the size, type of practice, and ownership of hospitals were effective on the degree of their Technical Efficiency. However, there was no significant correlation between teaching / non-teaching hospitals with Technical Efficiency.Conclusion: Establishment of competition system among hospitals, constitution of medium size hospitals and allocation of budget to hospitals based on national accreditation system are recommended.