The authors experineced 49 instances with dissecting aneurysm of aorta diagnosed by angiography from April 1981 to March 1987. We analyzed the technique of angiography, the method of procedure, and the angiographic findings. The results are as follows: 1. The most common site of arterial puncture for introduction of catheter was right femoral artery(38 cases), and we also used the left femoral(5 cases), right and left axillary, andbrachial arteries(eaach 3 cases) in cases in which the femoral arterial pulse is absent or feeble. In 5 among the45 cases of femoral arterial punctures, the catheter was introduced into false channe. We used conventional aortography (48 cases), IADSA (9 cases), and IVDSA (1 case). Although contrast injection for angiography was routinely twice per case( one for thoracic aortography and the other for abdominal aortography), but we did it 3times in 16 cases, 4 times in 9 cases, and 7 times in one case. 2. In a series of our 49 cases, the most common type classified by DeBakey et, al., was type III (28 cases), secondly tpye I (19 cases) and the third type II (2cases). According to Stanfor classification, the patient with type A were 28 persons and the patient with type Bwere 21 cases. 3. Angiographic findings were identified with following frequency: intimal tearing (33 cases),intimal flap with opacified false lumen(29 cases), compression of true lumen(24 cases), aortic wall thickness over6mm (19 cases), abnormal catheter course (12 cases), re-entry(10 cases), and aneurysm formation (8 cases). The most commonly involved branches are left renal and celiac arteries (each 16 cases).