Objective To assess the effectiveness of large-calibre (7.5#) transanal tube drainage and decompression on prevention from anastomotic leakage following anterior resection for rectal cancer. Methods Clinical data of 346 consecutive patients (M/F=1.39, age range 32-84 years, median age 58.5 years) undergone anterior resection for rectal cancer in this institute from January 2006 to December 2008 were analyzed retrospectively. Results The anastomotic leakage rate was 0 (0/185) and 5.59%(9/161) in patients with or without receiving large-calibre transanal tube drainage respectively. The anastomotic leakage rate was significantly decreased by large-calibre transanal tube drainage after anterior resection for rectal cancer (χ2=8.526, P=0.004). Eight cases of anastomotic leakage were treated conservatively and the other one required further surgical interventions. No perioperative death occurred in this series. Conclusion In this study, the large-calibre transanal tube drainage and decompression is effective in protecting rectal anastomosis and decreasing the rate of anastomotic leakage.