Mitochondrial neurogastrointestinal encephalomyopathy is a rare multisystem disorder characterized by gastrointestinal dysmotility, cachexia, ptosis with peripheral neuropathy, leukoencephalopathy and thin body habitus. The gastrointestinal motility studies are recommended for the diagnosis of the disorder. The mitochondrial alterations detected in the skeletal muscle biopsies are the main evidence in the diagnosis of the disease. We report a 31 years old female patient who was presented with acute diffuse peritonitis. She has been followed up by Neurology Department for mitochondrial neurogastrointestinal encephalomyopathy syndrome since three years. In surgical exploration we detected small bowel diverticulitis in a segment of ileum of 10 cm in length. In patients with chronic intestinal dysmotility history and in whom acute abdominal surgery is recommended, mitochondrial neurogastrointestinal encephalomyopathy syndrome must be taken into account in differential diagnosis.