PURPOSE: The proportion of sphincter-saving operations for lower rectal cancer is increasing with improved surgical techniques and additional concurrent preoperative chemo-radiation therapy. A defunctioning ileostomy or colostomy is performed after a sphincter-saving operation in the belief that diverting the fecal stream will prevent anastomotic leakage. This study was undertaken to assess all morbidity and combined problems associated with a temporary loop ileostomy. METHODS: A total of 167 patients who had undergone an ileostomy after a proctectomy between July 1997 and May 2007 were enrolled in this study. All patients were analyzed retrospectively, and the enrolled patients were registered in the Colorectal Cancer Database and were followed prospectively. Three patients did not receive an ileostomy take-down operation because of tumor recurrence. RESULTS: Complications of ileostomy formation developed in 20 (11.9%) cases. There were no significant relevant factors influencing the complications of ileostomy formation. Complications related with ileostomy take-down developed in 33 (17.9%) cases. Longer operation time, perioperative transfusion, and postoperative radiotherapy were statistically significant factors related to the complications of ileostomy take-down (P=0.047, P=0.019, P=0.042). After ileostomy take-down, six patients were identified with complications, such as a rectovaginal fistula or an anastomotic stenosis, related with rectal cancer surgery. CONCLUSIONS: The useful ileostomy sometimes carries certain morbidity; therefore, an ileostomy should be performed selectively, and the decision should be made with care. Also, a careful evaluation of the distal part of an ileostomy is necessary before and after an ileostomy take-down.