Carbon monoxide poisoning is one of the most serious health hazards in Korea. Although the incidence rate has been assumed to be the highest in the world, there has been no available reports as far as the annual & nation-wide incidence are concerned. Authors analyzed the incidence reports from 1965 to 1970 filed by the National Police & also made incidence survey on Seoul area in 1968 & 1969. The results of these surveys informed us that the official police reports are very much underevaluated. The stochastic estimations of the general incidence were made based on the informations which were obtained through incidence survey made in Seoul area. The findings obtained are as follows ; 1. The annual incidence of CO poisoning tends to increase since 1965. 2. The incidence is higher in the urban area & the incidence in Seoul is the highest in the world. 3. The frequency of incidence is the highest in the December. 4. The main causes of poisoning are the gas leakage from "ondol" floor & the leaking of gas from kitchen to room through the connecting door. 5. The incidence survey made in Seoul area revealed that the official police reports are underevaluated around one-eighth of actual incidence. 6. The health hazards induced by CO poisoning is greater than those caused by 19 Class I & Class II communicable diseases.