Three cases of Leigh disease (subacute necrotizing encephalomyelopathy) have been investigated recently in our institute by CT. Bilateral, low attenuation areas were observed in the basal ganglia in all cases. These areas corresponded to the typical necrosis areas seen pathologically in this disease. In our study there were further interesting CT appearances: the peripheral enhancement of low-density zones and the discovery of the lesions before the clear onset of clinical symptoms.