An important safety concern when exercising burned patients is the potential for an excessive increase in core body temperature (hyperthermia = body core temperature >39°C) during exercise. We examined the thermoregulatory response to exercise in the heat (31°C, relative humidity 40%) in a 17-year-old boy with a 99% TBSA burn. A 30-minute exercise test was performed at an intensity of 75% of his peak aerobic capacity. Intestinal temperature was assessed via telemetry with an ingestible capsule. Intestinal temperature was measured before, during, and postexercise. The patient completed 12 minutes of the 30-minute exercise test. Starting core temperature was 36.98°C and increased 0.69°C during exercise. After exercise, intestinal temperature continued to increase, but no hyperthermia was noted. It has been reported that burned children can safely exercise at room temperature; however, the response in the heat is unknown. This patient did not develop exertional hyperthermia, which we propose is due to his low-fitness level and heat intolerance. However, the potential for hyperthermia would be increased if he was forced to maintain a high relative workload in the heat. We propose that severely burned individuals should be able to safely participate in physical activities. However, the decision to stop exercising should be accepted to avoid development of exertional hyperthermia.