Operating rooms (ORs) are the most critical and expensive sector of healthcare facilities. The air conditioning system is designed to provide a well-controlled indoor air quality (IAQ). This design guarantees a perfect infection control and a good thermal comfort of patient and operating staff.This paper aims to analyze and evaluate indoor thermal comfort at different cases to assign the proper inlet air temperature to the OR. The predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD) models in accordance with ISO 7730 were used for this study.Field measurements were first carried out in an OR at Kafr El-Sheikh educational hospital to get the thermal environment parameters. These parameters are required to determine the thermal comfort indices namely (PMV & PPD). Four different cases of supplied air temperature 17.5, 18.5, 19.5 and 20.5oC were studied and compared through 105 measuring points distributed in the operating room. The PMV and PPD indices were computed at each case for three groups of medical staff: surgeons (metabolic rate equal to 120 W/m2), nurses and surgeon\u27s assistants (100 W/m2), anesthetists (70 W/m2).The results revealed that inlet air temperature has a minor effect on the air velocities and airflow patterns inside the OR at the same air change rate. For the current ventilation system, it is difficult to create a very comfortable work conditions for all operating staff at the same time due to their different thermal requirements. It was concluded that a supplied air temperature of 18.5oC provides almost comfortable conditions for all surgical staff
