DNA methylation degree in the several murine brain and liver genes of different ages and after scrapie infection have been examined by using methylation-sensitive restriction endonuclease digestion. We found that the methylation of c-fos and c-myc in the brain and liver was increased during the late fetal to one month postnatal developmental periods. However, those of the SGP-2, $S100{eta}$, APP950, PrP, and APLP1 genes were decreased at the same periods. The comparison of the DNA methylation patterns between scrapie infected brains and controls demonstrated there is no significant difference in methylation degree of scrapie-infected brains. These observations indicate that DNA methylation might be importantly related to the aging process. The scrapie-infected murine brain was not significantly developed more senescent than the same age-controls did.