Blunt duodenal injury in children is uncommon and diagnosis is often delayed because of its retroperitoneal location. Both diagnosis and treatment are difficult. We report the case of a 2-year-old boy whose trauma injury was not reported for 5 days. His vital signs were stable, but he was vomiting bile-stained fluid and his stools were white. The third portion of the duodenum was completely disrupted, and was repaired by pyloric exclusion with duodenal and bile duct drainage. The child recovered uneventfully. We discuss the diagnostic strategies and therapeutic measures for this type of injury.