Laryngeal carcinoma, as a malignant tumor that occurs in the head and neck region, is widely treated by radiation, but in some cases, the cancer is radioresistant to the radiotherapy. The reason for the radioresistant response needs to be clinically understood. We designed our present study to identify the molecules that may be involved in this radioresistant response. In this study, we initially established the inherent radioresistant (Hep-2max) and radiosensitive (Hep-2min) cell lines from the parental laryngeal cancer cell line Hep-2. Furthermore, using microarray analysis, we identified a novel inherent radioresistance-related gene, phosphoprotein associated with glycosphingolipid-enriched microdomains1 (PAG1). We showed that siRNA directed against PAG1 in a radioresistant (Hep-2max) cell line dramatically enhanced the radiosensitivity and IR-induced cell death. On the contrary, ectopic expression of PAG1 in radiosensitive (Hep-2min) cell lines led to radioresistance and suppressed the IR-induced cell death. Taken together, our results indicate that the PAG1 gene may be a novel, promising radiosensitization target for laryngeal carcinoma.