The authors experienced 49 instances with dissecting aneurysm fo aorta diagnosed by angiography from April 1981 to March 1987. We analyzed the technique of angiography, the method of procedure, and the angiographic findings. RESULTS : 1. The most common site of arterial puncture for introduction of catheter was right femoral artery, and we also used the left femoral, right and left axillary, and brachial arteries in cases in which the femoral arterial pulse is absent or feeble. 2. In a series of our 49 cases, the most common type classified by DeBakey et. al., was type III secondly type I adn the third type II. 3. Angiographic findings were identified with following frezuency : Intimal tearingm, intimal flap with opacified false lumen, compression of true lumen, aortic wall thickness over 6mm. abnormal catheter course, re-entry, and aneurysm formation.