Gastrointestinal complications may follow organ transplantation. A patient who underwent heart lung transplantation due to patent ductus arteriosus and Eisenmenger's syndrome had an episode of acute cardiac rejection and was treated with a bolus injection of methylprednisolone followed by a high oral dose of prednisone. On the 22nd postoperative day, the patient complained of acute abdominal pain with muscular rigidity and a plain chest x-ray showed free air in the right subdiaphragmatic area. Under the suspicion of bowel perforation, an emergency laparotomy was performed and the perforated stomach had a wedge-shaped resection that included the perforation. Following the laparotomy, the postoperative course was uneventful and the patient was discharged on post-laparotomy day 10.