Rupture of an aneurysm of the abdominal aorta is of infrequent occurrence. The correct diagnosis of this accident has rarely been made. This study is based on a survey of the literature and a personally encountered case. Kampmeier1 in 1936 reported 73 cases and reviewed the literature on the subject. He found 313 cases reported up to the time of his publication. Since his review, there have been reported 41 additional cases. The total number of cases in the literature is 427. We wish to add 2 cases, 1 of which is reported in detail. The autopsy records of the Mount Sinai Hospital since 1930 have revealed 1 case of rupture of an aneurysm of the abdominal aorta. The second case in the hospital records, described in this paper, makes a total number of 429 reported cases. Cases of abdominal aneurysm fall into two major groups, those in which