Acute type A arotic dissection is a condition which requires emergency surgery. Surgeons want to know not only the extent of the disease but also the exact site of intimal tear as well as the presence of side branch involvement to plan the extent of surgery. Various non-invasive diagnostic tools(transthoracic and transesophageal echocardiography, conventional and spiral computed tomography and magnetic resonance imaging) and invasive angiography are available for the evaluation of the extent of dissection, site of intimal tear and side branch involvement. Each technique has its advantage and disadvantage. Especially, MRI has been accepted as a gold standard for the diagnosis of aortic dissection, but it is immobile and sometimes it cannot give us the information about the small intimal tear site. Transesophageal echocardiography has the advantage of movability and high resolution in addition to the ability of providing comprehensive information about the cardiac function. Because of these advantages, it has been widely utilized for the evaluation of patients with aortic dissection. We performed preoperative transesophageal echocardiography in addition to computed tomography in 3 cases of acute type A aortic dissection and report these cases with the review of articles.