Two children with glycogen storage disease type 1B developed chronic inflammatory bowel disease. The first, a 7-year-old boy, had ileitis and later developed perianal disease. The second developed colitis by the age of 9 years; in both the features were consistent with Crohn disease. The children had neutropenia and neutrophil mobility defects characteristic of GSD-1B. It is suggested that these neutrophil abnormalities are important in the pathogenesis of the bowel inflammation.