Wernicke encephalopathy (WE) was first described by Carl Wernicke in 1881. WE is caused by thiamine deficiency. Alcoholism is the most common etiologic factor associated with WE in the United States, but it can occur in any patient with a nutritional deficiency state such as hyperemesis gravidarum, intestinal obstruction, and malignancy. WE is a clinical diagnosis. The common findings include mental status changes, ocular dysfunction, and a gait apraxia, present in only 10% of cases. Only a few cases of WE are diagnosed before death.