Retroperitoneal duodenal rupture due to blunt abdominal trauma is relatively uncommon. Diagnosis is difficult because the physical signs are subtle or they are difficult to interpret. A case of retroperitoneal duodenal rupture due to blunt abdominal trauma in whom the diagnosis was delayed is reported. Radiographic features are discussed. The role of early roentgen diagnosis is stressed in order to reduce the very high mortality which is associated with delay in diagnosis and treatment.