The authors report their experience in the treatment of 179 cases of colonic neoplasm between January 1985 and August 1992. Particularly, they emphasize the advantages of one-stage colectomy with anastomosis because of an obstructing carcinoma of the left colon, used on 41 cases. This treatment can be practicable by using the intraoperative "wash-out" technique. The one-stage colectomy with anastomosis can be advisable because the long survival can be compared to that deriving from the non obstructing carcinoma. Moreover this technique offers several advantages such as the one-stage treatment, the absence of colostomy, the improvement of the cost-benefit relationship, etc. On 41 cases treated by this technique, the authors lament only one decease caused by a total dehiscence of the anastomosis, notwithstanding reintervention. Moreover, 9 cases of partial dehiscence were treated by NPT (Total Parenteral Nutrition) except one which demanded a reintervention.