Background: In this study, we explored the relationship between                  neutrophil-to-lymphocyte ratio (NLR) and grade 3 or higher treatment related small bowel toxicity and treatment outcome of patients with rectal cancer undergoing capecitabine and concurrent intensity modulated radiotherapy (IMRT). Materials and Methods: From the year of 2012 to 2013, 117 rectal cancer patients who received concurrent chemoradiotherapy in our hospital were enrolled in this study. The association of baseline NLR level with grade 3 or higher treatment related small bowel toxicity and treatment outcome, including overall survival (OS) and progression free survival (PFS) were analyzed.  Results: The optimal cut-off value of the NLR was determined to be 2.2 for the OS according to the receiver operating characteristic (ROC) analysis. A higher level of the baseline NLR was associated with hypoalbuminemia (P= 0.018). No relationship between NLR level and grade 3 or higher acute as well as late treatment related small bowel toxicity was found. A multivariate Cox model revealed that lymph node metastasis (p= 0.013), distant metastasis (p< 0.001), and high NLR level (p = 0.032) were significant predictors for poor OS. Nevertheless, a relationship between NLR level and PFS was not found. Conclusion: This study show that higher baseline NLR level could not predict treatment related small bowel toxicity of rectal cancer patients who received capecitabine and concurrent IMRT. It is very gratifying to see that NLR is a useful predictor for treatment outcome of these patients.