The flow diagram of Goldberg and Sheft for the differential diagnosis of diseases of the small bowel was modified (using as its basis mucosal swelling, width of lumen, secretion). Its accuracy was then tested retrospectively in 61 patients. Examination of the small bowel was performed after the administration of a single large dose of contrast medium. A surprisingly high accuracy of 90% was found in 41 pathologically proven cases; all normal patients were correctly identified. The method therefore appears to be extremely promising. More detailed identification is not always possible because of similar reaction of the small bowel to various influences; it may be possible on some occasions, or when taking account of further radiological signs, or of the clinical and laboratory findings.