Previous statistical studies by the authors lent strong support to an aggressive policy of case selection in the surgical treatment of asymptomatic abdominal aortic aneurysms. To test further the value of narrow operative contraindications, the clinical course of 156 patients with such lesions, who between the years of 1952 and 1971 had been deemed unfit for surgical treatment, was surveyed. Among the 127 patients who never came to operation, 90 died during the 20-year followup period. Although organ-fixed atherosclerosis (mostly coronary) was the leading cause of death (55.0%), rupture of the aneurysm continued to be an important source of loss of life (27.8%). Upon the whole, the findings corroborated the validity of an aggressive surgical approach and emphasized the prognostic threat of aneurysmal size and arterial hypertension in the nonsurgically treated patient.