3 cases of dissecting aneurysm of the aorta and paraparesis are presented. 1 patient had an ascending dissection of acute onset with paraplegia but without pain. He was treated conservatively but the patient died. At autopsy a large coronary infarction was also found in the area of the right coronary artery, which was compressed at the starting point of the dissection. The second patient had momentary intensive chest pain and reversible paraparesis, and a descending dissection was seen in aortic angiography. He received hypotensive treatment and was symptomless when last seen 9 months after onset. The third patient had momentary intensive chest and back pain without any other symptoms. A descending dissection was found in aortic angiography and an operation was performed. During the operation the aorta was occluded for 57 min, which was too long for the medullary circulation and permanent paraplegia was the result. Modern diagnostic and therapeutic possibilities are discussed.