The macroscopic appearance of the shape of ulcerations and distribution pattern of the lesions was analyzed in 45 operated or dissected cases presenting inflammatory small intestinal diseases, in order to establish a basis for X-ray diagnosis. Characteristic macroscopic findings could be found for each inflammatory disease. The differential diagnosis of inflammatory small intestinal disease requires X-ray demonstration of the shape of ulcerations and their distribution pattern. The double contrast method is the best suited because it offers excellent visualization of the ulcerative lesions in almost every region of the small intestine on the survey films. The X-ray findings in 30 cases examined with the double contrast method in the two weeks preceding surgery were analyzed. The aspect displayed was correlated with the shape, size and position of the ulcerations. Differential diagnosis should essentially rely on the characteristic shape of the ulcerations and subsequently on the distribution pattern of the lesions on double contrast films. The theoretical differential diagnosis of inflammatory diseases of the small intestine should be done by confrontation of these findings.