This report is designed to review our experience in the past 9 years as a basis for critical evaluation of late complications of abdominal aortic surgery, and to explore methods of preventing some of the major complications of grafting procedures. Clinical Material Since March of 1952, 660 patients were operated upon for arteriosclerotic lesions of the aortoiliac system, using homograft or prosthetic material for repair. Of this group, 240 patients had aneurysms, and 420 patients had occlusive lesions. This presentation reviews the serious complications involving the graft or the anastomoses which occurred after the patients had recovered from the immediate postoperative period. It does not include early bleeding from graft or suture line, thrombosis of graft, or the complications of an abdominal operation not related to the graft. Three cases of colon necrosis, however, which occurred in the early postoperative period are included because of the grave nature of this