Lower gastrointestinal bleeding (LGIB) is normally treated conservatively or by noninvasive techniques. Emergency operations are only necessary when patients with severe hemorrhage cannot be stabilized by emergency endoscopy or angiography. To improve the postoperative outcome it is of importance to operate on the patients without any unnecessary time delay. If the preoperative localization of the bleeding source failed, a total or subtotal colectomy should be regarded as a safe procedure. A blind segmental resection should not be done. Alternatively, several ileotomies or colotomies might be performed in order to localize and treat the bleeding site. Elective surgery is indicated with chronic or recurrent bleeding that cannot be treated conservatively. A meticulous preoperative localization of the bleeding site, including anorectoscopy, endoscopy, angiography and nuclear scan is required. With reliable knowledge of the cause and localization of the suspected hemorrhage, a directed segmental bowel resection should be performed.