Involvement of the upper gastrointestinal tract (oesophagus, stomach, duodenum, jejunum) accounted for 13% of endoscopically proven Crohn's disease in patients at the University Clinic, Tübingen between 1973 and 1980. The basis for the diagnosis was the presence of epitheloid granulomas. The diagnosis was suspected in 26% of patients on endoscopic appearances alone. In these two groups, the appearances were similar, consisting of atypical or linear ulcers, cobble-stone lesions, chronic erosions, aphthous ulcers, stenoses, coarsening of the mucosa and areas of engorgement and granularity. Most patients were also examined radiologically. The radiological findings correspond with the endoscopic observations. Using a double contrast technique, mucosal changes could be demonstrated which, up to now, were only seen by endoscopy. If these findings are observed either radiologically or endoscopically, it is essential to examine the distal portions of the gut.