A review of 24,000 consecutive autopsies during a 23-year period from 1952 through 1975 at the Massachusetts General Hospital revealed 473 patients died with surgically intact arteriosclerotic abdominal aortic aneurysms (AAA). Contrary to previous studies, the incidence of rupture of AAA between 4 and 7 cm in our experience is similar and significant (25%). The location of rupture and duration of symptoms were recorded. Of the multiple-risk factors considered, only size seemed to bear on the likelihood of AAA rupture. Of 52 patients followed 3 months to 10 years before death with known AAA, the majority died of the ruptured AAA. In a surgical environment with an expected mortality of less than 2%, even small aortic aneurysms should be resected.