Background Aortic dissection occurs at a low incidence, but is associated with high mortality. It is generally acute onset, complicated and is often misdiagnosed; therefore is a macro vascular disease that poses major threat on patients’ lives. Timely diagnosis and management are essential, so we investigated the diagnostic value of multi-slice spiral CT in aortic dissection. Methods clinical data from 21 patients with confirmed aortic dissection were retrospectively analyzed. All patients had undergone plain and contrasted multi-slice spiral CT scans. Results true lumen and pseudo cavity were clearly revealed in all 21 patients, of which 17 showed intimal flap, four showed intimal calcification and inward displacement, while 2 had thrombosis in the pseudo cavity. As for classification among these 21 patients, 9 had type Ⅰ aortic dissection, including two patients with innominate artery involvement, 1 with celiac trunk involvement and 2 with left renal artery involvement; 2 had type Ⅱ aortic dissection, including 1 patient with innominate artery involvement; Another ten patients had type III aortic dissection, including 2 patients with left subclavian artery involvement and 1 with celiac trunk involvement. Nineteen out of 21 patients had clearly revealed initial rupture. Conclusion multi-slice spiral CT is characterized by rapidness, non-invasiveness and accuracy. It provides clear visualization of the location and scope of aortic dissection, location of the rupture as well as the valves, which makes it a first-choice imaging approach for the diagnosis of aortic dissection. Background Aortic dissection occurs at a low incidence, but is associated with high mortality. It is generally acute onset, complicated and is often misdiagnosed; therefore is a macro vascular disease that poses major threat on patients’ lives. Timely diagnosis and management are essential, so we investigated the diagnostic value of multi-slice spiral CT in aortic dissection. Methods clinical data from 21 patients with confirmed aortic dissection were retrospectively analyzed. All patients had undergone plain and contrasted multi-slice spiral CT scans. Results true lumen and pseudo cavity were seen clearly in all 21 patients, of which 17 showed intimal flap, of which four showed intimal calcification and inward displacement, while 2 had thrombosis in the pseudo cavity. As for classification among these 21 patients, 9 had type I aortic dissection, including two patients with innominate artery involvement, 1 with celiac trunk involvement and 2 with left renal artery involvement; 2 had typ e II aortic dissection, including 1 patient with innominate artery involvement; Another ten had had type III aortic dissection, including 2 patients with left subclavian artery involvement and 1 with celiac trunk involvement. Nineteen out of 21 patients had grained revealed initial rupture. Conclusion multi -slice spiral CT is characterized by rapidness, non-invasiveness and accuracy. It provides clear visualization of the location and scope of aortic dissection, location of the rupture as well as the valves, which makes it a first-choice imaging approach for the diagnosis of aortic dissection.