Objective The objective of this study was to investigate the relationship between the expression of RAD18 and radiation resistance in glioblastoma multiforme(GBM)and to provide a new therapeutic target for improving the radiation resistance of GBM.Methods Human glioma A172 cells were transfected into blank and RAD18-containing plasmid vector.The cell proliferation of two groups after the same dose radiation was detected by cloning assay.The mRNA expression of RAD18 in primary and recurrent GBM samples after close proximity treatment were detected by qRT-PCR.All data were analyzed statistically.Results The proliferation of GBM cells transfected with RAD18 plasmid was higher than that of cells transfected with blank plasmid after radiation therapy(P<0.001).The expression level of RAD18 mRNA in recurrent GBM was higher than that in the untreated radioactive granules primary GBM(P<0.01).Conclusion The resistance of recurrent GBM to radiotherapy may be associated with the overexpression of RAD18 protein.