Today, flexibility has turned to one of important issues in management theories and policies and most current discussions about flexibility patterns focus on management policies, so that these patterns are one of important aspects of human resources strategic management. This study was performed with the aim of assessing the flexibility rate of human resources and performance indexes of Tehran Medical Sciences University hospitals and determining the possible relation between these variables. The present study is descriptive – analytical which was conducted in cross-sectional form in 2015. The statistical population was selected by stratifies random sampling method as 317 persons from nursing, administrative and financial personnel of 5 hospitals of Tehran Medical Sciences University. Data collecting toll was hospitals performance indexes form and Wright & Snell flexibility questionnaire of human resources. Data analysis was performed using SPSS 18 software and with the aid of descriptive statistical indexes and linear regression analysis. The results showed that personnel ( human resources) had high flexibility = 4.16. there was a significant relation between total flexibility and the index of bed circulation so that by one unit increase in bed circulation space, normally, the average of total flexibility decreased 0.64 units ( p-value<0.05). The results showed that human resources of Tehran Medical Sciences University hospitals have high flexibility, so authorities and policy makers are suggested to adopt policies of human resources management for creating flexibility in human resources and improving hospitals performance and amending hospitals status.