The acute aortic syndrome (AAS) is described. Its pathophysiology is discussed for each of the three entities (penetrating aortic ulcer, intramural hematoma and aortic dissection). The natural history of these three pathologies is reviewed. Diagnostic features and investigation imaging techniques are summarized. The technique of stentgraft-placement is described in detail. The authors report their clinical experience with 127 patients, presenting acute type B aortic dissection or its variants, and treated with an endovascular stent-graft-device. These results are in part compared with a group of control patients with acute type B dissection, submitted to medical non-invasive therapy.