Objective：To discuss the relationship between defunctionign stoma in low anterior resection for rectal carcinoma and the incidence of anastomotic leakage.Methods: Totally 270 patients who received low anterior resection for rectal carcinoma(with the distance between anastomosis and anal edge being 6 cm or less) from Jan.2005 to Oct.2006 were included in the present study.Defunctioning stoma was performed in 113(41.9%) patients considered with high risk of anastomotic leakage.The clinicopathological data were used to construct database.SPSS 10.0 software was used to analyze the incidences of anastomosis leakage in patients with and without receiving defunctioning stoma.Results: There were 20(7.4%) leakages in the 270 cases.The symptoms included abdominal pain(37%),increase of pulse(53%),fever(47%),leukocytosis(53%),pelvic fluid properties change(68%),anal discharge of bloody fluid(26%) and others(10%).The average age of patients with leakage was 57.8 years.No death was caused by anastomotic leakage.Four(3.5%) leakages happened in defunctioning stoma group,and 16(10.2%) leakages happened in non-stoma group(P=0.04).Eighteen(75%) of the 24 patients with preoperative radiotherapy history received defunctioning stoma and none of them had leakage.Two of the 6 cases who had preoperative radiotherapy history receiving no defunctioning stoma had anastomotic leakages; the fisher exact probability test showed P=0.054.The leakage rate was 4.9% (7 cases) in 142 cases who had received protective measures during low anterior resection and the rate was 10.2%(13 cases) in the rest 128 cases who had not received any protective measures(P=0.10).Leakages subsided with conservative treatment in the 4 patients with stoma,but 8 patients without stoma had severe symptoms and required surgical intervention; one developed peritonitis.The average fasting periods were significantly different between the 2 groups(P<0.01).The postoperative obstruction incidence(P=0.24) and hospitalization stay(P=0.91) were not significantly different between the 2 groups.Conclusion: Anastomotic leakage is still the most important complication of anterior resection for rectal cancer,and a defunctioning stoma can undoubtedly reduce the rate of anastomotic leakage in high-risk patients.It is suggested that all the anterior resection cases with anastomotic height of or less than 6 cm should be considered for defunctioning stoma.