Bowel preparation is frequently impossible in various acute colonic diseases, such as left-sided colonic obstruction. The goal of intraoperative colonic irrigation is to obtain, during surgery, a bowel preparation offering the possibility of primary resection with immediate anastomosis, when pre-operative bowel preparation has not been feasible. Technical aspects of intra-operative colonic irrigation are described. Indications for this method are presented: left-sided obstructing carcinomas, diverticulitis, more rarely inflammatory stenosis or functional obstruction.