The findings on barium follow through, ileoscopy and biopsy of the terminal ileum in 46 children with suspected chronic inflammatory bowel disease have been compared to the final clinical diagnosis. Ileoscopy and barium follow through agreed in 91%, barium follow through and biopsy in 80% and barium follow through, ileoscopy and biopsy in 76% of cases. A pronounced lymphoid hyperplasia pattern was present radiologically in 24%, and was a source of error in two cases. Barium follow through compared favourably to ileoscopy or biopsy individually, detecting 18 of 20 and 17 of 20 cases respectively; however, ileoscopy combined with biopsy diagnosed every case. The sensitivity of the barium follow through was 0.90 with a specificity 0.96 for the diagnosis of Crohn's disease in the terminal ileum.