Patients who have inflammatory bowel disease occasionally develop severe complications or emergency situations that require expert and expedited medical care, including toxic colitis, fistulas, abdominal abscesses, malignancy, primary sclerosing cholangitis, and pouchitis. Morbidity and mortality rates of Crohn's disease and ulcerative colitis are increased over the expected rates in the unaffected population. Knowledge of the presenting features, natural history, and treatment of these complications should to lead to early and effective therapy and better outcomes.