Although the occurrence of Wernicke's encephalopathy (WE) in patients on dialysis is frequently alluded to, review of the literature reveals only 3 described cases. We describe 5 patients on dialysis who developed WE in the absence of alcoholism or other predisposing factors. The clinical diagnoses included uremic encephalopathy (2 patients), dysequilibrium syndrome (1), dialysis dementia (1), and brainstem hemorrhage (1). At postmortem examination, classic findings of WE were evident. The rarity of WE in patients on dialysis may in part be explained by studies indicating a genetic defect in transketolase activity. Patients on dialysis are also potentially at risk for thiamine deficiency because of anorexia, vomiting, and intravenous alimentation. Other factors altering thiamine requirements, such as glucose load or infections, may also contribute. Preventable and potentially curable, WE should be suspected in all patients on dialysis who have an unexplained neurological picture.