Background: The capability for DNA double-strand breaks (DSBs) repair is crucial for inherent radiosensitivityof tumor and normal cells. We have investigated the clinicopathologic significance of DNA repair gene expressionin nasopharyngeal (NP) carcinoma. Materials and Methods: A total of 65 NP cancer patients who receivedradiotherapy were included. The immunopositivity to Ku 70, DNA-PKcs, MRN, RAD50, XRCC4, and LIG4were examined in all tumor tissues. Results: The patients comprised 42 males and 23 females, with a median ageof 56 years (range, 18-84). The expression levels of RAD50 (0,+1,+2,+3) were 27.7%, 32.3%, 21.5%, and 18.5%.LIG4 (±) were 43.1% and 56.9% respectively. The 5-year OS rate of patients with LIG4 (±) were 90% and67.9%, respectively (p=0.035). The 5-year TTP rate of patients with LIG4 (±) were 75.9%, 55.5%, respectively(P=0.039). Conclusions: Our results suggest the possibility of predicting the radiosensitivity of NP cancer byperforming immunohistochemical analysis of LIG4.