Of a total 712 patients with left-sided colorectal cancer, 79 (11%) required emergency surgery due to severe obstruction by tumors. Of these 79 patients, 55 underwent tumor resection and anastomosis. Primary resection and anastomosis with intraoperative bowel irrigation was performed in 44 patients (primary group), while staged resection and anastomosis was performed in only 11 (staged group). In comparing the two groups, there was no significant difference in the rates of curative resection, being 76% versus 90%. However, the primary group demonstrated significantly lower rates of postoperative wound infection (P < 0.001), anastomotic dehiscence (P not equal to 0.05), and postoperative mortality, at 2% versus 18% (P < 0.05). The cumulative survival curve was also better in the primary group (P < 0.05). These favorable results of the primary group were confirmed by analyses which established that no bias of therapeutic backgrounds existed in either of the two groups. Thus, it was concluded that for left-sided obstructing colorectal carcinoma, intraoperative bowel irrigation, followed by primary resection and anastomosis, produces more advantageous results.