Background: Though total mesorectal excision (TME) has proved to effectively decrease local recurrence rate of mid/low rectal cancer, the efficacy of preoperative radiotherapy in Asian patients remains unclear. The present study aimed to compare the efficacy of TME alone versus TME after preoperative radiotherapy and simultaneous chemotherapy with capecitabine plus oxaliplatin in Chinese patients with stage II and III mid/low rectal adenocarcinoma. Methods: Patients (n=192) aged between 18 and 70 years enrolled from March 23, 2008 to August 2, 2012 were randomly divided into two groups. Group A (n=97) received preoperative radiotherapy and simultaneous chemotherapy [46-50 GY/23-25 with oxaliplatin 100 mg/m² (D1) and capecitabine 1,000 mg/m² (bid, D1-15), repeated since D22], which was followed by TME; while patients in group B (n=95) underwent TME alone. While disease free survival (DFS) was the primary endpoint; the following were evaluated as secondary endpoints: pathological response rate, pathologic complete response (PCR) rate, anal preservation rate, local recurrence rate, distant metastasis rate, acute toxic effects, and late toxic effects. Results: Excluding the drop outs, 90 and 94 patients were analyzed in group A and B, respectively. The median follow-up time was 29 (range: 0 to 59) months. PCR was achieved for 32 patients (35.6%). The median survival time and overall survival (OS) rate in group A were 24 months and 92.5% (95% CI: 88.3-96.7), respectively; while the same were 34 months and 88.7% (95% CI: 84.8-92.6) in group B. The median DFS time was 22 and 31 months in group A and B, respectively; and the overall DFS was 86.1% (95% CI: 81.6-90.6%) and 80.6% (95% CI: 74.8-85.4%) in both groups. No significant differences were observed between groups in OS rate (p=0.323), overall DFS, (p=0.612), and anal preservation rate (p=0.849). Conclusions: Preoperative radiotherapy combined with chemotherapy of capecitabine plus oxaliplatin could result in higher PCR rate. However, studies with long follow up and large sample are recommended to demonstrate the efficacy of this treatment strategy over TME alone. Clinical trial information: ChiCTR-TRC-00000122.