Abstract: Objective To investigate the effect of antisense VEGF on the radiation sensitivity of esophageal cancer cells in vivo.Methods 16 male BLBA/C/nu nude mice were randomly divided into 4 groups and prepared cells were subcutaneously injected on the paw pat of mice(2×10 6/100μl/mice): The volume of the subcutaneous tumors was measured before and after irradiated and transfected.The effect of treatment was assessed by tumor growth delay . The expression level of VEGF were examined in different groups by RT-PCR ,western blotting respectively..Results The absolute growth delay (AGD)for antisene group, irradiation group and antisene plus irradiation group was3.0±2.6, 10.1±5.4 and 27.4±3.1 days,and nominal growth delay (NGD) was 24.4±3.1 days . The enhancement factor of antisense VEGF for radiotherapy was 2.41.The decreased expression level of endogenous VEGFmRNA and protein were found in antisene group by RT-PCR and western blotting analysis.Conclusions Combining Antisense VEGF and radiotherapy could enhance radiotherapic effect for esophageal cancer xenografts