This is the first reported case of survival of a significant burn in a patient with established Addison's disease. The systemic stress response to thermal injury is well recognised, there is a marked hypermetabolic response with prolonged periods of catabolism. In particular, the elevation of plasma cortisol levels is crucial for this response to severe systemic stress. Cortisol elevation is maintained for the duration of burn wound healing, is proportional to the burned body surface area and the normal circadian rhythm of endogenous cortisol is lost. Acute adrenal insufficiency has been described in patients suffering major burn injuries with generally poor outcomes. We discuss the management and complications of adrenal replacement therapy in a severe burn setting, as illustrated by this case report.