Summary:A case study is presented of a patient with alcohol amnestic (Korsakoiff's) syndrome in which magnetic resonance (MR) imaging demonstrated mamillary body atrophy. The patient never developed a full spectrum prodromal Wernicke's encephalopathy. Neuropsychological studies indicated significant shortterm memory deficits in the presence of generally intact intellectual functions. This case study supports the role of specific mamillary body involvement in the memory deficits associated with Wernicke–Korsakoff syndrome, that mamillary body atrophy can be detected by MR scanning, and that mamillary body atrophy can develop in the absence of a complete Wernicke's encephalopathy