Cases of so-called "upside down stomach", or volvulus of the stomach prolapsing into the mediastinum, are rare. We encountered a patient of advanced age who developed a large esophageal hiatus hernia with an upside down stomach, which was surgically treated. An 89-year-old female patient had repeated vomiting and hematemesis requiring emergency hospital admission. Upper gastrointestinal contrast study revealed severe esophageal hiatus hernia and gastric volvulus resulting in the stomach turning upside down. Computed tomography showed prolapse of the large portion of the stomach into the mediastinum. Because the patient had undergone epigastric laparotomy, surgery was initiated with opening the upper abdomen followed by returning the stomach into the peritoneal cavity. The hiatus hernia was sutured, and floppy Nissen fundoplication was performed as well as stomach fixation under the diaphragm. The patientʼs food intake was favorable postoperatively, and she was discharged.