Congenital diaphragmatic hernia through the foramen of Bochdalek may present after infancy. A 21/2-year-old Malay girl presented with acute respiratory distress. Chest examination showed reduced chest expansion and decreased breath sounds on the left side. Chest radiograph showed a large "cyst" in the left chest, which was thought to be a lung cyst under tension. Tube thoracostomy resulted in clinical improvement. Results of a barium study showed that the cyst perforated by the thoracostomy tube was the stomach, which had herniated through a Bochdalek diaphragmatic defect. Surgical repair of the diaphragmatic defect and closure of the perforated stomach was performed successfully. Congenital diaphragmatic hernia should be included in the differential diagnosis of respiratory distress in young children. Nasogastric tube placement must be considered as an early diagnostic or therapeutic intervention when the diagnosis is suspected.