Delayed herniation of abdominal contents through a congenital diaphragmatic hernia may occur beyond the neonatal period. The case of a 29-month-old child with a Bochdalek hernia presenting as acute respiratory failure is presented. Chest radiography showed a tension gastrothorax that was misread as a tension pneumothorax. Tube thoracostomy resulted in clinical improvement by perforating and decompressing the stomach. Nasogastric tube placement confirmed herniation of the stomach into the left chest and is the initial treatment of choice when a tension gastrothorax is identified. A congenital diaphragmatic hernia must be recognized promptly so that rapid gastric decompression and surgical repair of the diaphragmatic defect can be performed.