The purpose of this study was to evaluate and determine the environmental performance index (EPI) of the Social Security Organization in the field of treatment. The statistical population of this study included all 880 employees of the Social Security Organization of Mazandaran province in the field of treatment in 2016. The sample size of the population was 268 according to the Cochran formula. Sampling was conducted using simple random method. Researcher-made questionnaire was used in order to collect information. The validity of the questionnaire was confirmed by the supervisor and its reliability was confirmed by Cronbach's alpha. In order to analyze the data, Kolmogorov-Smirnov test and one-sample T test were used. Results have shown that water, habitat, child mortality, and air quality are considered the EPI Environmental Performance Indicators of the Social Security Organization. The results also showed that child mortality, air quality, habitat, water, and sanitation had a higher priority among the EPI environmental performance indicators of the Social Security Organization in the field of treatment.
