Although stapling colorectal anastomosis is widely accepted as an alternative for hand-sewn anastomosis, we continue to experience postoperative complications such as anastomotic hemorrhage and leakage, which sometimes lead to serious morbidity or even mortality. To secure stapling colorectal anastomosis, we adopted intraoperative colonoscopy (IOCS). We performed IOCS in 73 cases of colorectal resection with stapling anastomosis from November 2004 to October 2005. Intraoperative colonoscopy revealed active bleeding from stapling anastomosis in 7 patients (9.6%). Of these, additional sutures were done in 6 patients, while the anastomosis was exteriorized in the other. The air leak test performed by IOCS was positive in 4 patients (5.5%), with additional sutures being done in 2 patients and reanastomoses performed in the other 2. Incomplete cutting of the mucosa was found in one patient, but it was successfully managed. Following the introduction of IOCS, there were no cases of postoperative anastomotic hemorrhage, and only one case of anastomotic leakage (1.4%).