Surgical treatment of chronic inflammatory bowel disease Abstract. Surgery is an important mainstay in the treatment of inflammatory bowel disease. Despite considerable progress in anti-inflammatory treatment approaches, two thirds of patients with Crohn's Disease will need surgery during their lifetime. Indication for surgery are therapy-refractory disease courses and complications such as perforation, stenosis, or abscess. In Ulcerative Colitis, about one third of patients will require surgery. These patients are operated for therapy-refractory or complicated colitis or the development of dysplasias or carcinomas. Choosing the optimal time-point for surgery can be very challenging and requires a good interdisciplinary collaboration. Recurrence rate of intestinal Crohn's Disease is high, and recurrences can occur in the neoterminal ileum or on other bowel segments due to the panenteric pattern of Crohn's Disease. This is in contrast to Ulcerative Colitis, where a total proctocolectomy can imply cure for the inflammatory as well as the malignant component of disease. In the following chapter we will elucidate the current surgical treatment of Crohn's Disease and Ulcerative Colitis with respect to new treatment aspects and current scientific background.