[ ABSTRACT] AIM:To compare the differences of the genome-wide methylation levels and methylated regions be-tween nasopharyngeal carcinoma ( NPC) cells in the same genetic background but different radiation resistance ( CNE-2 cells and CNE-2R cells).METHODS:Using the method which was developed by Doctor Zhao Cun-you, based on using methyl-sensitive restriction enzyme to measure the genome-wide methylation levels.In addition, MeDIP-Seq was used to analyze the methylated regions in 6 gene functional elements, including the upstream 2k sequence, 5’ UTR, coding se-quence, intron, 3’UTR and downstream 2k sequence, between CNE-2 cells and CNE-2R cells.RESULTS:The genome-wide methylation level was approximately 30%lower in CNE-2R cells than that in CNE-2 cells.No obvious difference on the amount of genes and the coverage of the peak in the 6 gene functional elements was observed.However, the methylation pattern of plentiful genes had altered in the gene function elements.CONCLUSION:The genome-wide methylation levels and methylated regions between NPC cells in the same genetic background but different radiation resistance were quite dif-ferent, indicating that the DNA methylation may be associated with NPC radioresistance.