Diaphragmatic hernia complicating pregnancy is rare and results in a high mortality rate, if early surgical intervention is not undertaken. We report a case of a woman at 32 week's gestation who was admitted to our hospital due to severe epigastralgia. Diaphragmatic relaxation had been pointed out since her birth. The patient was initially diagnosed with acute gastritis, but she developed acute respiratory insufficiency on day 3 of hospitalization. Chest X-ray and computed tomography showed niveau in the left pleural cavity. She was treated with chest tube drainage and an emergency caesarean was performed. The next day, gastric fiberscope demonstrated perforation of gastric ulcer in the left hemithorax. She was diagnosed as having diaphragmatic hernia complicated by a perforated stomach. Emergency thoracotomy was carried out and primary repair of both stomach and diaphragma was performed.