Sepsis-associated encephalopathy (SEA) is a diffuse brain dysfunction secondary to the systemic response to infection and is associated with high mortality rate. We report a 4-year-old boy with SEA. He presented with abdominal pain and vomiting. On the second day of admission, he developed consciousness disturbance with impaired attention, confusion and delirium. Routine laboratory tests, brain magnetic resonance imaging and cerebrospinal fluid examination were normal. Electroencephalography (EEG) showed high-voltage slow wave activity on the right hemisphere with epileptiform discharge. He immediately underwent surgery and a torsed, gangrenous Meckel's diverticulum with extension of ischemia to adjacent small bowel was seen and resected. His consciousness had become normal by the third day and he was discharged without any sequela. To overcome a poor prognosis in patients with SEA, the early recognition of the symptoms of SEA and also appropriate treatment of the underlying cause are essential.