Strenuous exercise leading to heat stroke is known to cause rhabdomyolysis and acute renal failure in men, but there are no reports of this environmental illness in otherwise healthy women. We report the first case of heat and exercise induced acute renal failure in a young nonacclimated adult female following intense exertion in the Grand Canyon. This individual displayed the typical clinical features of exertional heat stroke including hyperpyrexia, CNS disturbance, rhabdomyolysis, oligoanuric acute renal failure, and disseminated intravascular coagulopathy. The pathophysiology is discussed as well as sexual differences in response to heat and exercise. The specific factors that may have predisposed this young woman to heat stroke from exertion are identified.