Objective: To identify the most suitable plane for division of the inferior mesenteric artery in laparoscopic-assisted radical resection of rectal cancer. Methods: The clinical data of rectal cancer patients from July 2008 to January 2012, who underwent laparoscopic-assisted radical resection with the division of the inferior mesenteric artery in different planes, were comparatively analyzed. Results: In patients with vascular division at the root of the inferior mesenteric artery during surgery (334 cases), the parameters that included the average operative time (7.8 min vs.12.6 min) and average blood loss (4.8 mL vs.12.5 mL) in management of the inferior mesenteric artery, and the average number of dissected lymph nodes around the inferior mesenteric artery and abdominal aorta (12.5 vs.10.9) were all significantly better than those in patients with vascular division at a point 2-4 cm distant from the root of the inferior mesenteric artery (153 cases), and all the differences had statistical significance (all P<0.01). There was no significant difference in the incidence of injury of inferior mesenteric plexus between the two procedures (P>0.05), and no intestinal ischemia occurred in any of the patients. Conclusion: Division at the root of the inferior mesenteric artery in performing laparoscopic-assisted radical resection of rectal cancer is safe and reliable. Moreover, it has the advantages of shorter operative time, less blood loss and adequate lymph node clearance.