Five children (three boys, two girls) presenting in the first year of life with intractable diarrhoea had a number of features in common. All had ulcerating stomatitis, four had partial villous atrophy on small intestinal biopsy, all had colitis characterised by large ulcers with overhanging edges, and four had severe perianal disease; no stool pathogens were detected. Treatment with steroids, sulphasalazine, and azathioprine was unsuccessful. All five required subtotal colectomy. Four were children of consanguinous marriages, two were siblings of Pakistani origin, two were cousins of Arab origin, and the fifth was Portuguese. Although the diagnoses of Behçet's disease and Crohn's disease were considered, it appears that these children represent a distinct inherited condition affecting the whole gastrointestinal tract, particularly the colon.