Effective rewarming devices have only become available recently. This investigation compares the efficiency of an new overhead radiant heater (ARAGONA Thermal Ceilings TM, CTCX, 1000 W) with that of an electric blanket (50 W) or a standard hospital blanket. 35 patients undergoing postoperative assisted ventilation and continued sedation were randomly assigned to one of the treatments. Shivering, oxygen uptake, heart rate and invasive blood pressure were measured and the increase in total body heat minus body heat production was calculated as heat balance. Results are given as medians (range). Subcutaneous temperatures were taken to calculate the mean skin temperature. The evaluation was undertaken for an oesophageal temperature interval of 35 degrees to 37 degrees C. All groups exhibited a similar mean oxygen uptake i.e. thermogenesis (3.5 (2.7-4.0) ml.kg-1.min-1, 3.3 (2.7-4.9) ml.kg-1.min-1;3.2 (2.4-5.1) ml.kg-1. min-1) which correspond to a resting energy expenditure. The time of rewarming of the radiant heat treated group (n = 12) (100 (76-143) min) for this interval was significantly reduced in comparison to both other groups (183 (116-320) min; 231 (115-340) min). A slightly positive heat balance was only achieved in the group treated by radiant heat, indicating that all metabolic heat was conserved or heat losses were compensated by transfer of external heat. Shivering was significantly reduced in the radiant heater group whereas the rate pressure product was insignificantly higher. We did not find any significant effect for the electric heating blanket in comparison to the control group.(ABSTRACT TRUNCATED AT 250 WORDS)