Abstract: Objective To investigate the role of the clock gene promoter methylation in aging. Methods C57BL mice of 4- (young, n=9) and 20- (old, n=10) month-old were determined the promoter methylation level of clock genes (Per1/2, Bmal1/2, Cry1/2, Clock, Npas2) in the stomach, spleen, vascular, kidney and striatum with methylation-specific polymerase chain reaction (MSP). Results The incidence of promoter methylation of Cry1, Bmal2 and Npas2 in spleen increased in old mice (P<0.05), while the promoter methylation of Per1 in stomach decreased (P<0.05), and the promoter methylation of Bmal1 in vascular increased (P<0.05). Conclusion Promoter methylation of some clock genes is involved in process of aging in a tissue-specific way.

Key words: aging, circadian rhythm, clock genes, promoter methylation