As the number of obese patients increases, as will the number of bariatric procedures. Malabsorptive bariatric procedures have emerged as one of common causes of Wernicke encephalopathy (WE), an acute neuropsychiatric disorder due to thiamine deficiency. However, restrictive procedures such as sleeve gastrectomy (SG) are less prone to cause nutrient deficiencies. WE occurred after SG is an uncommon complication because the main absorptive sites for thiamine are intact after SG. Here, we report a case of WE after SG. With rapid increase in the use of SG for morbid obesity, this case deserves particular attention from clinicians.