Carbon monoxide (CO) poisoning is a common occurrence in today's society. Most such poisonings are a direct consequence of inhaling the toxic byproducts of combustion. Exposure to toxic amounts of CO occurs most often during inhalation of automobile exhaust or smoke resulting either from faulty heating systems or industrial accidents. CO poisoning is associated primarily with injury to the brain and the heart because the gas binds to hemoglobin and interferes with these organs' need for a continuous supply of oxygen. Prompt recognition of CO poisoning and treatment of the patient with oxygen are essential to prevent long-term damage and delayed neurologic sequelae.