Intercostal herniation of lung caused by nonpenetrating thoracic trauma is rare in the pediatric population. An 11-year-old boy presented with such a hernia 4 years after the original injury. The hernia was increasing in size and was becoming more difficult to reduce. In view of possible future strangulation, a surgical repair was undertaken with prosthetic mesh closure of the intercostal muscle defect. Intercostal hernias are rare, but familiarity with the proper investigation and treatment to be provided is important.