Etiologic factors and prognosis of delayed postanoxic encephalopathy (DPE) was analyzed in 30 patients admitted in Yeungnam University Medical Center from March, 1984 to April, 1987. Twenty-three among the 30 cases was possible to be followed. The results are as follows. 1. The incidence in over 30 years of age was 77%, and sex ratio was 1:1.7 for male and female. 2. The lucid interval of DPE was from 5 to 191 days (mean=19 days) and interval between 3 to 4 weeks occupied 60%. 3. The longer the duration of exposure to CO and the more comatous of the mental state, the more increased was the incidence of DPE. 4. The hyperbaric O2 threapy had no influence on the incidence of DPE but absolute bed rest on acute CO poisoning ws important to prevent DPE. Therefore, absolute bed rest during lucid interval at least 2 weeks is more important factor to prevent DPE. 5. DPE victims are likely to retire from his social position.