Early recognition and diagnosis of Wernicke encephalopathy is pivotal for the prognosis of this medical emergency, especially in patients with liver failure which predisposes individuals to develop hepatic encephalopathy. For these patients, distinguishing between hepatic encephalopathy and Wernicke encephalopathy is a challenge in real-world clinical practice.A male patient with 21-year medical history of liver cirrhosis presented diarrhea and ascites. One month before this visit, he was noted to have poor appetite and progressive fatigue. After admission, although several major symptoms, including diarrhea, ascites, hyponatremia, and hypoproteinemia, were greatly improved through appropriate treatments, his laboratory indicators were not changed much. His appetite was not reversed at discharge. On the 5th day after discharge, the patient suddenly became reluctant to speak and did not remember the recent happenings. Simultaneously, unsteady gait and strabismus occurred. On the basis of clinical manifestations and brain magnetic resonance imaging scan results, the patient was diagnosed as Wernicke encephalopathy and these relative symptoms were resolved after intravenous vitamin B1.To our knowledge, this is the second case report of Wernicke encephalopathy developing in a critically ill cirrhotic patient without hepatocellular carcinoma or operative intervention. Wernicke encephalopathy may be underdiagnosed in these patients and this case raises physicians' awareness of its possible onset.