An increasing number of patients with inflammatory bowel disease (IBD) have been observed over the past two to three decades at the Cleveland Clinic. This has allowed extensive follow-up and determination of long-term prognosis. The diseases are chronic, require medication over a long period of time, are frequently associated with the need for operation, and often have complications and recurrences. In addition, a substantial number of patients have onset disease at a young age and thus, the propensity for recurrences and complications makes IBD of significant clinical importance. The symptoms of IBD are chronic and usually include diarrhea and often malnutrition. Rectal bleeding is found in almost all patients with ulcerative colitis and in about 25% of patients with Crohn's disease. However, severe hemorrhage in IBD occurs in a small number (1-5%) of patients. When this occurs, it often does so as an episode which may be associated with severe illness systemically as well as creating diagnostic confusion. For patients with ulcerative colitis, the progressive severity of bleeding may be an important indication for surgery (colectomy); in Crohn's disease, patients with ileocolic location of disease are more likely to have severe hemorrhage, and may require resection as a result. Despite the similarities of Crohn's disease and ulcerative colitis, there are significant differences particularly in the long-term (greater than 10 years) follow-up. For patients with Crohn's disease, the major long-term problem is the need for surgery (2/3-3/4 of patients) and recurrence (+/- 50%).(ABSTRACT TRUNCATED AT 250 WORDS)