This paper analyses the results of comparative clothing thermal insulation measurements determined in tests on volunteers and on a thermal manikin under specified conditions, ie a standing man and a standing manikin in a climatic chamber under wind-free conditions. The tests were performed with three ensembles of disposable medical clothing. In tests with a thermal manikin, the heat balance was determined and the temperature and heat losses on the manikin’s surface were measured, whereas in tests with volunteers, calculations were made for dry heat losses under the conditions of heat comfort. Clothing thermal insulation values obtained in tests on a manikin and on human subjects were then compared. The results showed the following: 1) thermal insulation of clothing ensembles determined on human subjects was 13% higher than that measured on the manikin; 2) the measurements taken on the manikin were considerably more accurate than those taken on tests with volunteers (manikin’s error 2%, subjects’ error 12-18%).