Providing a safe and comfortable indoor environment for the patient and medical staff is one of the primary tasks in the operating room (OR) environment. These rooms typically use two ventilation systems: mixing ventilation (MV) and unidirectional airflow (LAF). In addition to ensuring adequate air quality, these systems shape the conditions of the thermal environment in the operating field and, consequently, the heat exchange processes between human body and the environment and the thermal sensations of patients and all medical staff in the operating room. The present study was designed to test whether the thermal conditions in the microenvironment and on the operating table are sufficiently different for the LAF and MV systems to result in different thermal sensations for users. This study was carried out in an operating room laboratory, where the heat generated by the medical staff was simulated using thermal manikins, while the patients were female and male volunteers. The volunteers’ thermal sensations were collected every 30 min by means of a questionnaire comprising questions on thermal sensations, air movement and thermal sensations of individual body parts. The survey revealed differences in the sensations of the respondents depending on the ventilation system used.