Abstract: A 23-year-old woman was rescued from an accidental fire in a state of cardiopulmonary arrest. Based on the diagnosis of carbon monoxide (CO) poisoning, she received hyperbaric oxygen therapy and survived in a vegetative state. After 1 and a half years, she died without recovering from the vegetative state. At autopsy, the brain was observed to be moderately softened with a severely atrophied appearance and ventricular enlargement. In addition, a characteristic damage of hypoxic-ischemic leukoencephalopathy was also observed clearly in both the bilateral globus pallidus and cerebral white matter, which are typical findings of past acute CO poisoning. A long-term vegetative state causes the brain to soften and liquefy because of reactive gliosis and autolytic change. The cause of death becomes difficult to diagnose only from the autopsy findings in general. This case is rare in that the past acute CO poisoning could be diagnosed from the remaining typical cerebral findings even after a long-term vegetative state.