There is no disease that would have as many and variable complications as Crohn's disease. One of the most common complications is bowel obstruction which can be caused by the angulation of the bowel or by inflammation, or by formation of granulation tissue (32.3%). Very common is the formation of fistulae amongst the bowels involved and other abdominal organs, and also entero-cutaneous fistulae occur frequently (11.3-14.4%). The frequency of complications is increasing with the duration of the illness. If they are life-threatening, only surgical treatment can help. Surgical treatment is also indicated when conservative treatment fails. The most commonly used surgical interventions are bowel resection and, recently, the plasty of stenotic areas. The operative mortality (3.7%) is influenced by the length of the disease and by the numbers of complications. Recurrence is very common in Crohn's disease (30.1-34.9%). The mortality rate of the second operation is 17.5%. The prognosis is usually poor because recurrence can occur years after the primary operation. In Hungary, the frequency of surgically treated patients with Crohn's disease is low, they count for 0.06% of all general surgical operations.