BACKGROUND Refeeding syndrome (RFS) is a life-threatening syndrome, which can cause sudden death. RFS has been reported frequently in young patients with anorexia without organic disease; however, there are few reports in elderly patients with organic disease. Herein, we report a case of cardiac arrest after refeeding syndrome associated with hiatal hernia. CASE REPORT We report the case of a 59-year-old woman who had a diagnosis of RFS during treatment for anorexia secondary to hiatal hernia. She was hospitalized with hypothermia, anemia, and hypovolemic shock and treated with electrolytes, hydration, and transfusion at the Emergency Department. Upper gastrointestinal endoscopy revealed hiatal hernia with severe reflux esophagitis. We initiated parenteral nutrition (8.7 kcal/kg/day). However, QTc prolongation caused pulseless ventricular tachycardia. Temporary cardiac pacing was performed to prevent recurrence. Her nutritional status steadily improved, and she was transferred to another hospital without complications. CONCLUSIONS Patients with gastrointestinal comorbidities are more likely to have inadequate food intake and to be undernourished on admission and therefore should be carefully started on nutritional therapy, considering their risk of RFS.