THIS STUDY is an attempt to define the factors important in the selection of patients for abdominal aortic aneurysmectomy. Of particular concern is the question: should all patients with an abdominal aortic aneurysm be operated on regardless of the extent of their generalized vascular disease. The correlation of successful therapy with certain preoperative, operative, and postoperative findings suggests that selected individuals may be better managed without aneurysmectomy. Material and Results One hundred consecutive patients had their abdominal aortic aneurysms replaced electively with synthetic prostheses in the Barnes Hospital between January 1, 1957, and December 31, 1964 (Table 1). During this period 24 other individuals were operated on for ruptured abdominal aortic aneurysms. These cases are not included in this study. The mean age of the patients treated was 64 years. Eighty-six were men (Table 2). The 100 patients can be divided into four groups: 17 individuals who died in the