The mechanism of right-sided traumatic diaphragmatic hernia following blunt trauma was examined. In 13 cases of Traumatic diaphragmatic hernia admitted to the Department of Traumatology Osaka University Hospital, 3 cases were on the right. All cases were associated with severe injuries in the chest, abdomen and pelvis. Rib fractures, hemothorax, and liver injury were seen in the same site of the ruptured diaphragm. So it seemed that there were some differences in the force itself caused diaphragmatic rupture between right-sided and left. We reviewed 40 cases of right-sided traumatic diaphragmatic hernia reported in Japan. The following results were obtained. Main force which caused right-sided diaphragmatic rupture was the blunt impact to the right thoracic wall. In the right-sided diaphragmatic hernia, the most frequently herniated organ was the right lobe of the liver and there was high-frequency of G-I tract herniation in delayed types. Herniation of the abdominal organs seemed to be varied as the time passed.