Life-threatening herniation of intra-abdominal viscera through a patent Bochdalek foramen is well recognized in neonates. Persistent foramina, leading to clinical problems in adult life, are very rare. In the case of the 17-year-old girl described in this paper, two-thirds of the stomach had inverted and passed into the left side of the chest as had the splenic flexure of the colon and most of the greater omentum. There was 500 mL of blood free in the peritoneal cavity and 1200 mL in the left pleural cavity, with no hernial sac. The defect measured 5 cm in diameter. It was repaired primarily after reduction of the viscera. Prompt operative intervention is recommended in such cases to prevent strangulation and bleeding from engorged viscera.