Approximately 15% of patients with ulcerative colitis develop an acute attack of severe colitis, and 30% of these patients require colectomy. Severe ulcerative colitis is therefore considered a medical emergency, the management of which requires close collaboration between gastroenterologists and surgeons. The mortality rate for patients with severe ulcerative colitis is now <1% in specialist centers, but it was high before intravenous steroid therapy and early surgery were introduced; indeed, mortality is still high in nonspecialized centers. As colectomy severely affects quality of life, therapy with intravenous ciclosporin and, more recently, infliximab has been introduced to try to avoid the need for surgery. Ciclosporin induces short-term remission, but the long-term benefit remains unsatisfactory as colectomy is often only delayed. A significant short-term reduction in the colectomy rate has, however, been observed after infliximab treatment. The use of infliximab versus ciclosporin in patients with severe ulcerative colitis remains to be defined. The timing of surgery remains a cardinal decision in the management of severe ulcerative colitis; increased morbidity resulting from prolonged ineffective medical treatment and, therefore, a delay in surgical treatment should be avoided.