Progress in p53 and retinoblastoma (Rb) gene methylation is introduced. CPG dinucleotides are the hot spots of DNA methylation and mutation. CpG dinucleotides of p53 and Rb gene are easily methylated. Hypermethylation of the tumor-suppressor genes. with consequent gene inactivation and the loss of the suppression of the cellular proliferation. has been postulated as one of the potential mechanism for oncogenesls.