ObjectiveTo provide basis for radiotherapy of nasopharyngeal carcinoma (NPC) in different stages via comparing the radiosensitivity of NPC cells 610B and HNE2.MethodsNPC cells 610B and HNE2 were used for radiosensitivity test. Their sensitivities to radiotherapy were detected by colony formation test. Cell cycle was monitored by flow cytometry. Apoptosis in different groups was inspected by flow cytometry and Western blot. Immunofluorescence combined with Western blot was used to measure the phosphorylated histone γH2AX reflecting the level of doublestrand DNA damage induced by radiotherapy.ResultsThe results of colony forming experiment showed that HNE2 (IC50≈3.5 Gy) was more sensitive to radiotherapy than 610B (IC50≈5 Gy). The results of cell cycle showed that both cells showed G2Mphase cycle arrest after radiotherapy. DNA damage and cell apoptosis.ConclusionHNE2 is more sensitive to radiotherapy than 610B, which provides reference for the treatment of NPC at different stages.