There is an established relationship between epidermal growth factor receptor (EGFR) expression and tumor cell proliferation and irradiation resistance.Here, we compare the enhanced irradiation response of the anti-EGFR antibodies cetuximab and nimotuzumab in esophageal carcinoma cell lines of differing levels of EGFR expression.Flow cytometry revealed that TE-13 and TE-1 cells expressed high and low levels of EGFR on the cell surface, respectively.Western blot analysis revealed that the radiation-induced EGFR phosphorylation was inhibited by cetuximab and nimotuzumab in TE-13 cells but not in TE-1 cells.The two antibodies significantly enhanced the irradiation response of the TE-13 cells, with cetuximab more effective at enhancing cellular sensitivity to irradiation and radiation-induced apoptosis compared with nimotuzumab.The disparity in modulation of irradiation response by the two antibodies could be associated with their efficiencies at blocking the radiation-induced activation of EGFR downstream signaling.The two antibodies did not affect the radioresponse of TE-1 cells.This effect may be related to the level of EGFR expression on the cell surface.