Background: The aim of this study is to compare clinical outcomes between two groups of different chemoradiation Regimens. Methods: Eligible patients were randomly assigned to Patients received either IMRT to the pelvis of 50 Gy/25Fxs concurrent with oxaliplatin 50 mg/m2 weekly and capecitabine 625 mg/m2 bid d1–5 weekly (Arm A), or IMRT to the pelvis of 50 Gy/25Fxs and a concomitant boost of 5 Gy to the primary tumor in 25 fractions, followed by a cycle of XELOX two weeks after the completion of chemoradiotherapy (Arm B). Surgery was scheduled eight weeks after the completion of CRT. All patients were recommended to receive adjuvant CT regardless of pathological stages. A total of six cycles of XELOX chemotherapy was recommended including neoadjuvant and adjuvant period. The primary end point was pCR. Results: From February 2010 to December 2011, a total of 120 patients were randomly assigned to Arm A (n = 60) or Arm B (n = 60). One hundred and ten patients (Arm A = 53, Arm B = 57) underwent surgery, the other 10 patients didn’t receive surgery because of unresectable disease. Eight and 14 cases were evaluated as pCR in two groups respectively (p= .157). Tumor response was further classified into good response and poor response, the former was defined as ypT0N0, ypT1-2N0 and ypT0N1a. The rate of good responses were 30.0% and 55% (p= .006). No significant differences were found in grade 3 or 4 acute adverse events during the treatment between the two groups. However, number of patients who had delayed incision healing was 13 and 3 patients (p= .007). There were no statistical differences in OS (p= .553), DFS (p= .349) and local-regional control (p= .856) between the two groups. In the univariate analysis, N stage, MRF involvement and tumor response had significant impacts on OS, DFS and LC. In the multivariate analysis, MRF involvement had significant impacts on OS (p= .02), DFS (p= .01) and LC (p= .01). Conclusions: A dose-intensified radiotherapy in neoadjuvant chemoradiotherapy demonstrated contribution to tumor regression with acceptable toxicity, but led delayed incision healing after surgery. The impact of MRF involvement on survival merits further investigation. Clinical trial information: NCT01064999