A case of coma due to Wernicke's encephalopathy complicated by respiratory failure is described. Ventilation and thiamine administration lead to recovery, although Korsakoff's psychosis and ataxia persisted. A review of similar cases of coma emphasizes the absence of diagnostic features, but that if structural disease is excluded the presence of pupillary and ocular signs may support a diagnosis of Wernicke's encephalopathy. The response to thiamine may be diagnostic as in 8 of these patients who received it, but the long-term morbidity remains high.