This study was undertaken to identify the causative factors that predispose to early postoperative intestinal obstructions after the radical resection due to colorectal cancer, and to determine their preventive operative techniques. The records of 722 patients that had undergone radical resection due to colorectal cancer at the Department of General Surgery, Kangbuk Samsung Hospital, between January 1, 1986 and December 31, 1995, were reviewed. Among them, operative treatments due to early postoperative intestinal obstructions were performed in 39 patients(5.4%). The most common cause of intestinal obstruction in early postoperative period was bowel adhesion, that was developed in 20 cases(51.3%), and next common cause was internal herniation of bowel into the space between colostomy loop and lateral peritoneal wall(3 cases, 7.7%), incarcerated herniation of small bowel into the reperitonealized pelvic cavity(3 cases, 7.7%), pelvic abscess(1 case, 2.6%), and unknown causes(9 cases, 23.1%) in descending frequency. Use of closed suction drains was responsible to development of the 3rd and 4th causes. As a result, during the radical resection due to colorectal cancer, meticulous manupulation of bowels not to injure the bowel serosa, reperitonealization of pelvic floor at narrow interval with inversion of its dissected edge, complete closure of the space between colostomy loop and lateral wall of peritoneum, and adequate alternative use of closed suction drain and natural drain according to the operative condition, should be considered. In conclusion, surgeons should pay more attention to the operating procedures to lower the incidence of early postoperative intestinal obstruction.