The indication for surgery is a balance between the severity of the disease despite full medical treatment and the potential disadvantages of surgery. The decision requires cooperation between gastroenterologist and surgeon. Colectomy with ileostomy and preservation of the rectum in the emergency setting is the accepted procedure and can rapidly restore the patient to normal health allowing withdrawal of anti-inflammatory medication. After recovery all surgical possibilities are then open for the future. The elective indications for surgery include failure of medical treatment, retardation of growth in a child or adolescent and neoplastic transformation. The choice of operation includes conventional proctocolectomy, restorative proctocolectomy (RPC) and colectomy with ileo-rectal anastomosis. Each has relative advantages and disadvantages. RPC is the commonest procedure. It offers a satisfactory outcome in 70-90% of patients with a cumulative failure rate of 10-15% over a 10 year period. Causes of failure include sepsis (50%), dysfunction (30%) and pouchitis (10%). In selected cases salvage surgery to avoid failure can be successful with rates of around 70% for outlet obstruction and fistulation and 50% for pelvic sepsis.