BACKGROUND The syndrome of Wernicke's encephalopathy consists of two of four features of (1) dietary deficiency; (2) oculomotor abnormality; (3) cerebellar dysfunction; and (4) confusion or mild memory impairment. Predisposing risk factors include alcoholism, hyperemesis gravidarum and prolonged intravenous feeding. METHODS A 35-year-old female developed refractory emesis, severe weight loss, and hypokalemia following banded gastroplasty for morbid obesity. Reversal of gastroplasty was performed four months following initial surgery. Following reversal, the patient developed confusion, ataxia, leg weakness and nystagmus. RESULTS Examination of the patient demonstrated disorientation with confusion, vertical nystagmus worse on downgaze, diffuse weakness of the lower extremities, and bilateral dysmetria. Magnetic resonance imaging of the brain demonstrated symmetrical areas of increased T2 signal present bilaterally in the medial thalamic nuclei. The patient did not demonstrate any initial improvement with intravenous thiamine but improved over two months of follow-up. CONCLUSIONS Wernicke's encephalopathy has been reported in the European literature as a complication of gastroplasty, with rare recognition of this clinical entity in the North American literature. This potential complication of gastroplasty may be preventable by nutritional intervention in subjects experiencing severe weight loss and emesis following surgery.