Objective: To investigate the application value of postoperative chemoradiotherapy in elderly patients with stage III rectal cancer. Methods: The clinical data of 128 consecutive elderly patients (≥75 years of age) with stage III rectal cancer treated from January 2010 to January 2014 were retrospectively analyzed. Patients were divided into chemoradiotherapy group (60 cases) and control group (68 cases) according to whether or not they received postoperative chemoradiotherapy. The progression-free survival, 2-year survival, health-related quality of life and postoperative complications between the two groups were compared. Results: In chemoradiotherapy group compared with control group, the progression-free survival was significantly prolonged [(793.58±295.39)d vs. (736.59±305.38)d, P=0.029], 2-year survival had an increasing tendency, but did not reach a statistical significance (91.7% vs. 79.4%, P=0.052), the score of higher health-related quality of life at 12 months after operation was significantly increased (70.25 vs. 63.37, P<0.001), the local recurrence rate was significantly reduced (16.7% vs. 33.8%, P=0.035), and the incidence of radiation enteritis (13.3% vs. 0.0%) and myelosuppression (11.7% vs. 0.0%) were significantly increased (P=0.002, P=0.004). There was no significant difference in incidence of intestinal fistula, intestinal obstruction and anemia between the two groups (all P>0.05). Conclusion: Though postoperative chemoradiotherapy increases the rate of postoperative complications, it can significantly improve the long-term outcomes in elderly patients with rectal cancer.