COMPRESSION of the stomach or intestine by the fluoroscopist with the gloved hand or a wooden device was a natural development of the roentgen method of examination of the gastrointestinal tract. By this maneuver flexibility of the wall of the stomach, crater shadows not brought into profile, and mucosal folds could be demonstrated. After Forssell (1) described the formation of gastric mucosal folds by the independent movement of the muscularis mucosæ, Åkerlund (2), Berg (3), and others emphasized the clinical importance of mucosal relief studies with relatively small quantities of barium suspension. They devised apparatus for making a permanent record on films during fluoroscopy of portions of the gastro-intestinal tract while pressure is being applied. Compression films provide greater detail than the fluoroscopic screen and can be studied at leisure. Although they do not displace careful fluoroscopic observation, undoubtedly more information can be obtained with than without them. It is obvious that pressure cannot be applied to certain regions of the alimentary tract, for example, the esophagus and the fundus of the stomach. The apparatus is just as important in those cases, however, as it permits the making of roentgenograms instantly when just the right amount of barium suspension is present to show the mucosal contours and when the patient is in the optimum position. The earlier workers with this type of equipment were interested primarily in compression studies of the stomach and duodenum. Less has been written about its application to diagnostic problems in other sections of the alimentary tract. We have the impression that in our department almost as many compression films are made of the small intestine as of the duodenum. This communication will deal with some experiences in the use of rapid shift-over equipment, either with or without compression, in the examination of the esophagus, the small and the large intestine. The cases presented herewith have been selected to illustrate a method rather than pathologic processes. Apparatus This type of apparatus consists essentially of two elements in addition to the usual fluoroscopic equipment. The first is a combination of fluoroscopic screen and cassette tunnel so arranged that the film can be quickly shifted into place in the beam of x-rays. Compression can be secured in a number of ways but the most convenient is a small cone attached to the screen-holding frame in such a way that it can be moved into the field without delay. The second element is a device for the instantaneous changing of the low fluoroscopic current to a sufficiently high roentgenographic current to permit an exposure of a quarter of a second or less, in the majority of cases. The earliest machines developed in Europe for this purpose were arranged for the examination of patients in the erect position only.