Heat-related illnesses are part of a continuum comprising heat cramps, heat exhaustion, heat syncope and heat stroke, and are associated with significant morbidity and mortality, especially in a tropical country like India. Heat stroke, which is the most severe, is caused by failure of thermoregulation with elevation of core temperature to 40°C (104°F) or more, associated with central nervous system dysfunction. The two important principles in management of heat stroke are lowering of core temperature immediately to 38.9°C and supporting organ systems injured by heat, hypotension, inflammation and coagulopathy. It is important to initiate cooling as fast as possible and keep the individual adequately hydrated to prevent complications.