The DNA repair ability of tumor cells is closely correlated with tumor chemosensitivity.  Promoter methylation of DNA may lead to transcriptional inactivation, gene silence and alteration of protein expression of DNA repair related genes, which in turn influences the ability of DNA repair, and therefore leads to the intrinsic and acquired tumor chemoresistance. This article briefly summaries the relationship between tumor chemoresistance and promoter methylation of DNA repair related genes such as O6-Methylguanine-DNA methyltransferase (MGMT), human mutL homologue 1 (hMLH1) and Fanconi anemia complementation group F (FANCF).