The radiological investigations relevant to chronic IBD are described briefly with emphasis placed on compression techniques in small bowel studies. A classification for reporting small bowel Crohn's disease is proposed, where the disease is staged as early, advanced or complicated, and the extent of involvement measured directly from the film. The terminal ileum may be normal in 20% of children with proximal Crohn's disease, so that ileoscopy should not be used to exclude small bowel disease. Radiological assessment of the small bowel is important in management. Surgical referral was based on the radiological changes in 6% of patients, and in 24% the presence of extensive uncomplicated small bowel Crohn's disease led to treatment with elemental diet. The use of some specialized examinations, such as the instant and ileostomy enema, are discussed.