Carbon monoxide poisoning is a major cause of accidental morbidity and mortality in Taiwan. Epidemics of carbon monoxide poisoning commonly occur during winter months and its sources include: smoke from fires, fumes from heating systems burning fuels, and exhaust fumes from motor vehicles. The signs and symptoms are relatively nonspecific, which often misdiagnosis of a flu-like viral illness and may range from nausea and headache to profound central nervous system dysfunction. Carbon monoxide causes tissue hypoxia, globus pallidus damage as well as diffuse white mater lesions and encephalopathic changes. It is clear that venous carboxyhemoglobin levels are similar to arterial levels. An early clue to the presence of carbon monoxide poisoning is a decreased measured oxygen saturation in the presence of a high PaO2. Hyperbaric oxygen therapy is an effective method in treating carbon monoxide intoxicated patients. Prevention depends on adequate ventilation, with venting of combustion devices to the outside air.