The present study was designed to evaluate the utility of the XRCC1 Arg399Gln and ERCC1 Cys8092Ala SNPs, measured in pretreatment biopsy samples, as predictors of response to radiotherapy in patients with non-metastatic nasopharyngeal carcinoma (NPC). The gene discussed is XRCC1; the disease is nasopharyngeal carcinoma.