Patients between the ages of 8 and 75 years of age with Crohn s disease or ulcerative colitis or symptoms of inflammatory bowel disease may be eligible for this study. Screening tests may include the following: medical history and physical examination, routine blood tests, examination of stool specimens, X-rays such as barium enema or upper GI series, proctosigmoidoscopy, colonoscopy, gastroduodenoscopy, and small bowel biopsy.