Abstract: ObjectiveTo explore the effects of Cetuximab combined with radiation on radiosensitivity, apoptosis and cell cycle progression of nasopharyngeal carcinoma (NPC). MethodsHuman NPC cell line CNE2 was treated with cetuximab, radiation or their combination.Using clonogenic survival, radiosensitivity was investigated.The Sigmaplot 10.0 software was applied for fitting the cell survival curve by single-hit multi-target model and linear-quadratic model. Apoptosis and cell cycle were measured by flow-cytometer. Results The radiosensitivity of CNE2 was enhanced by cetuximab and the sensitization enhancement ratio (SER) was 1.157.Radiation plus cetuximab significantly enhanced the radiation-induced apoptotic rates in CNE2 cell (P<0.05).By flow-cytometric analyses, G2/M arrest was induced in the NPC cells exposed to cetuximab alone.Furthermore, combined treatment resulted in synergistic effect on G2/M arrest in NPC cells. Conclusion Radiosensitivity of NPC cell lines was enhanced after exposure to cetuximab through promoting radiation-induced apoptosis and inducing cell cycle arrest.