Traumatic dissection of the aorta is a fatal injury that requires rapid diagnosis and treatment. In assessing acute thoracic aortic injury, transesophageal echocardiography (TEE) has recently compared favorably with standard diagnostic modalities such as computed tomography, magnetic resonance imaging and aortography. These latter include time-consuming, contrast injection and the transportation of the patient to another area, requiring the interruption of resuscitative efforts. But, TEE includes less invasive nature, shorter procedure time, no contrast injection, portability at bedside, ability to be done concurrently other procedures such as resuscitation or hemodynamic monitoring and has high sensitivity and specificity for the evaluation of trauma patients with suspected injuries of the thoracic aorta. TEE may be suggested as primary diagnostic modality in suspected traumatic aortic injury in emergency department. We report two cases of traumatic aortic dissection diagnosed early by transesophageal echocardiography in the emergency department.