To inhibit local recurrence of rectal cancer, it is very important to ensure that there is a sufficient circumferential resection margin. We evaluated pathology studies of combined radical resection of seminal vesicles in the treatment of rectal cancer. We analyzed data from 7 cases of combined radical resection of the seminal vesicle in the treatment of rectal cancer; we also analyzed data from 35 control cases without seminal vesicle resection. The circumferential resection margin averaged 5.97 mm for cases that had combined radical resection of the seminal vesicle, and this was significantly longer than for cases without resection (P < 0.001). Local recurrence was not seen in cases that had combined radical resection of the seminal vesicle, whereas 3 cases (5.9%) occurred in the group that did not undergo resection. Combined radical resection of the seminal vesicle in patients with rectal cancer ensures that the distance of the circumferential resection margin is sufficient to inhibit local recurrence.