Carbon monoxide intoxication is the most prevalent cause of death from carbon monoxide poisoning. We herein report the case of a 56-year-old man who was found unconscious and smelled of smoke after exposure to carbon monoxide from a heater. He scored 5 on the Glasgow Coma Scale, and had respiratory insufficiency and elevated troponin I, creatine kinase-MB fraction and carboxyhaemoglobin levels. He was treated by mechanical ventilation. After regaining consciousness, brain magnetic resonance imaging showed diffusion restriction in the left occipital lobe; there was a loss of vision (right temporal hemianopsia), which improved by the follow-up session. Carbon monoxide intoxication may cause neurologic and cardiac sequelae, and the initial treatment includes oxygen therapy. Acute carbon monoxide poisoning can cause serious injury to the brain, heart and other organs; the most severe damages that could be inflicted to the brain include cerebral ischaemia and hypoxia, oedema, and neural cell degeneration and necrosis.