There is comparatively little in the literature in regard to chronic duodenal ileus, and in my experience the condition has been quite rare. The first case in the group discussed in this paper was observed in 1919, and since that time, in 30,000 admissions to the hospital, there have been fifteen cases which definitely fall into this class as we have defined it. The relationship between acute duodenal ileus with acute dilatation of the stomach produced by compression of the root of the mesentery has been frequently stressed, and it seems reasonable to suppose that chronic ileus may have a similar etiology. In the Harvard museum there is a series of casts of the duodenum from cadavers showing the various types, and many of these show on the anterior surface a groove which corresponds with the line of the superior mesenteric artery. This corresponds to the usual point of obstruction