THE subject of this paper has been covered very thoroughly by many writers. Some years ago Dr. James T. Case reviewed the literature on the subject and discussed it in detail. Later on, Dr. E. Wyllys Andrews reported a number of cases. We do not wish to claim anything original, but merely a further study, or, rather, discussion of a subject which to our mind is very interesting. A diverticulum is a pouch or cul de sac, whether normal or abnormal, leading from a main cavity. Diverticula may be due to traction or pulsion, and may be congenital or acquired. There are true, false, or pseudo-diverticula. In the small bowel, they usually occur near the mesenteric attachment. According to Stengel, they owe their origin to localized weakness or separation of the muscle fibers of the bowel. Protrusion of the mucosa takes place, probably due to increased pressure from within; the pouch is, therefore, a hernious protrusion of the mucosa and serosa. It has been our experience to find extraluminal shadows in the second part of the duodenum rather common. Diverticula of the jejunum and ileum have been found very infrequently in our routine work, a fact which may not be due, however, to the infrequency of the lesion, but to the difficulties encountered in making a satisfactory study of these parts of the gastro-intestinal tract. In the large bowel, diverticula are met with very frequently, the sigmoid and the descending colon being the favorite locations. In reviewing many thousand gastro-intestinal examinations done during the past ten years we have identified only three cases of diverticula of the small bowel beyond the duodenum. Two of these cases showed a single diverticulum in the jejunum and the other showed multiple lesions in the jejunum and ileum (proved at operation). This last case will be taken up in detail later on in the paper. In going over many cases of duodenal diverticula we have been impressed with the frequency of accompanying diverticula of the large bowel. In our series of some fifty cases of diverticula of the duodenum, a large number have also had extra-luminal shadows in the large bowel. It may be that there exists a constitutional predisposition to their formation: it may be that there is some defect in the muscle of the bowel at the site of the blood vessels or ducts, as these are the favorite locations for their development. In reviewing the histories of these patients showing diverticula of the duodenum, we have been particularly impressed with the close resemblance of their symptoms to those due to duodenal ulcers. Most of the patients complain of some form of gastric distress. The usual clinical diagnosis accompanying these patients to the roentgen department is duodenal ulcer. It is not uncommon to find the symptoms quite typical of an ulcer; at other times the symptoms may be vague or absent.