Three cases of Wernicke's encephalopathy in nonalcoholic patients diagnosed by postmortem examination were reported to improve the recognition of this disease. All three cases were male, ages ranged from 33 to 73 years old. All the cases had a clinical history of malnutrition but no history of chronic alcoholism. Routine autopsy and neuropathologic investigations examining the histological changes of the brain were performed. Pathological findings included recent petechial and local hemorrhages in the mamillary bodies, periventricular regions around the third and fourth ventricles and aqueduct. Under light microscopy the proliferation and dilatation of the capillaries was particularly prominent in the mamillary bodies and pericapillary hemorrhages were present in the periventricular regions. Neuronal losses were found only in the medial nucleus of the thalamus and inferior olive, myelin staining demonstrated demyelination and gliosis in those areas. The diagnosis of Wernicke's encephalopathy was made. In combination with the reviewed literature, our cases suggest that Wernicke's encephalopathy can occur not only in patients with alcohol abuse, but also in those who have suffered thiamine deficiency due to metabolic and nutritional disorders.