Abstract: The promoter of early growth response gene-1(Egr-1) is a cis-acting element of Egr-1, and its activity is regulated by inducers such as ionizing radiation, free radical.In designated gene-radiotherapy system, radiation combined with therapeutic gene (such as tumor necrosis factor-αgene, suicide gene) can spatially and temporally regulate therapeutic gene expression in the irradiated field, produced a marked effect, while little systemic toxicities were observed.The combination of radiotherapy and gene therapy is promising in tumor therapy.