Aortic dissection is medical and surgical emergency. About 5 cases, the authors emphasized the role of transesophageal echocardiography in the diagnosis of aortic dissection. For all patients we realized a clinical examination, electrocardiogram, chest X ray, thoracic and transesophageal echocardiography and laboratory studies. Echocardiography were performed by an apparatus Hewlett Packard sonos 1000 with colour doppler and multiplanar transesophageal. Transesophageal echocardiography made the diagnosis by showing dilatation of aorta, intimal flap, false channel; this exam also allow to classify the aortic dissection.