Abstract: Objective To investigate the effect of notch1 siRNA blockade on the apoptosis and radiosensitivity of human glioma cell line U87-EGFRvⅢ. Methods All siRNAs were transfected into U87-EGFRvⅢ cells by Lipofectamine. The protein expression and mRNA levels of notch1 gene were detected by Western blot and RT-PCR. The AnnexinⅤ-FITC/PI assays were used to detect the inhibitory effect on cell apoptosis. The radiosensitivity parameters of U87-EGFRvⅢ cells were obtained by colony forming assay. Results The expression of notch1 mRNA and protein were significantly reduced by notch1 siRNA(P<0.05). The notch1 siRNA could significantly increase the cell apoptotic rates, compared with the control group(P<0.05). The primary result of colony forming assay showed that notch1 siRNA could enhance the radiosensitivity of U87-EGFRvⅢ cells. Conclusion Down-regulating notch1 expression could enhance the apoptosis and radiosensitivity of U87-EGFRvⅢ cells, which provides useful information for the basic research of notch1 gene in the radiotherapy and combined targeted therapy on glioma.