THROMBOSIS of the abdominal aorta with gradual complete occlusion of one or both common iliac arteries undoubtedly occurs more frequently than is commonly realized. In an autopsy series from the Metropolitan State Hospital (for the insane) in Massachusetts, there were 13 instances in a series of 382 consecutive cases.1 This is an unusually high incidence, and a more typical experience is reported from the Cleveland City Hospital, where there were nine cases in the autopsy material from 1930 to 1939.2 Although in a few instances the thrombosis was thought to be secondary to such conditions as polycythaemia vera and Buerger's disease,3 the majority of reported cases have resulted from ulceration of atheromatous deposits at the bifurcation of the aorta. Until recent years, most instances of primary aortic thrombosis were undiagnosed clinically. Leriche, in 1940, published an account of a case treated by resection of the aortic bifurcation