We report a case of Wernicke’s encephalopathy in a patient with nasopharyngeal carcinoma with a 3-month history of poor oral intake related to nausea and vomiting due to chemotherapy. The patient later developed deep coma while receiving in-patient therapy. Magnetic resonance imaging of the brain revealed typical findings of Wernicke’s encephalopathy. The patient was treated with thiamine injections, which resulted in subsequent partial recovery of neurological function. This paper stresses the importance of magnetic resonance imaging for prompt diagnosis of Wernicke’s encephalopathy.