Key Clinical MessageCardiopulmonary bypass for trauma patients carries the risk of bleeding from injured organs, while traumatic aortic dissection can progress rapidly. It is sometimes difficult to determine the optimal time for aortic repair in trauma patients.AbstractAn 85‐year‐old woman was diagnosed with traumatic ascending aortic dissection, right clavicle and left first rib fracture, and abdominal contusions after a vehicle accident. After admission, the aortic dissection progressed, and emergent surgery was performed. Although the risk of hemorrhagic complications needs to be evaluated, prompt aortic repair is required.