The clinical manifestations of delayed neuropsychiatric sequelae after carbon monoxide (CO) intoxication are variable. In addition, there is no specific therapy for these complications. Fortunately, these complications have occurred less frequently in recent years, probably due to the usage of hyperbaric oxygen (HBO) therapy. We report an 8-year-old boy who developed late psychiatric disturbances 2 days after full recovery of consciousness from initial CO intoxication. His neuropsychiatric symptoms included consciousness disturbance, motor dysfunction, chorea, aphasia and agnosias. He received HBO therapy at 2.0 barr for 60 minutes once a day for 7 consecutive days. Three weeks later, he was functioning normally with no neuropsychiatric symptoms. A literature review concluded that HBO may be effective in treating neuropsychiatric sequelae. Moreover, immediate administration of HBO during acute CO intoxication may prevent these complications.