Background Hypothermia is a common battlefield trauma occurrence. This study compared the effectiveness of the hypothermia, environmental, exposure, and trauma (HEET) garment (Trident Industries, Beaufort, SC) with and without thermal inserts with a control group of two wool blankets in the prevention of hypothermia in a treated hypovolemic porcine model. Materials and methods Five female swine (Sus scrofa-Yorkshire cross) were assigned to each of three groups: HEET with thermal inserts (n=5); HEET without thermal inserts (n=5); or control (n=5). After the animals were anesthetized and stabilized for 30min, the swine were hemorrhaged to a mean arterial pressure (MAP) of 30mm Hg, simulating a battlefield injury. Hetastarch 6% (500mL) was rapidly administered, simulating initial field resuscitation. One hour later, the animals' shed blood was reinfused, simulating transfusion at a field medical facility. The investigators moved the animal into a cooler set at 10°C±0.5°C. A pulmonary artery catheter was used to monitor core body temperature over a 6-h period. Results A repeated measures ANOVA and Tukey's post hoc test were used to analyze the data. There was a significant difference between the groups. At the end of 6h, the mean core temperature for the HEET with inserts group was 32.69°C±1.5; the HEET without inserts, 31.02°C±1.8; and control, 34.78°C±1.2 (P<0.05). While all groups became hypothermic, the wool blanket group was most effective in maintaining body temperature closer to normothermia. Conclusion The HEET garments with and without heaters are ineffective in preventing hypothermia.