Carbon monoxide (CO) is a kind of freq uent toxic gas around our living lives, for common use of briquet as fuel, and its pathologic effect has been known due to mainly hypoxia and direct cytotoxicity in some part to almost all organs, especially to the brain and heart. Some authors have reported pathologic and anatomic changes of the acute of posioning, although in a few cases, that bilaterally symmetrical lesions of the globus pallidus or cerebral white matter regarded as typical. After using computed tomography (CT), those findings have been discovered more easily and acurately. Authors analysed CT find ings of 32 cases, who had a history of acute CO posioning and performed CT at Hanyang University Hospital from May 1979 to June 1983. The results were as follows: 1. Of all 32 cases with CT scan, low density lesions were demonstrated in 28 cases (88%) and others were hemorrhagic and calcified in 2(6%), respectively. 2. AII lesions were seen as bilaterally symmetrical, exce pt 2 cases of hemorrhage and 1 of low density . 3. Of all 28 cases of the low densities, 15 cases(53.6%) were located in the globus pallidus, 10(35.7%) in the cerebral white matter and 3( 1 0.7%) in both of them. 4. Of all 13 cases of the low density lesions in the cerebral wh ite matter, common locations were in the frontal and parietal lobes (65.6%), and more in frontal (40.6%). 5. Of all 13 cases of low density lesions in the cerebral white matter, cases of involving all of the lobes were found in only 4. 6. All of 2 cases of the cal c ified lesions were seen at both sides of the globus pallidus, symmetrically. 7. All of 2 cases of the hemorrhage were seen at thalamus, ventricles and head of caudate nucleus, and these locations were different from those of the low densities or calcifications.