A follow-up study by CT and MR of a case of Wernicke encephalopathy is reported. In the early stages, CT and MR revealed a characteristic topographical distribution of lesions in the midbrain, pons, and thalami. In the later stages, MR showed atrophy of the mamillary bodies and midbrain tegmentum and dilatation of the third ventricle. Both CT and MR are useful tools for the diagnosis of Wernicke encephalopathy in the early stages.