Sirtuins (SIRTs) are involved in multiple cellular processes including those related to aging, cancer, and a variety of cellular functions including cell cycle progression, DNA repair, and cellular proliferation. SIRTs have been shown to extend the yeast life span, although there is presently little known about SIRT expression in the organs of mice. In the present study, we were especially interested in identifying differences in SIRT expression between young mice and aged mice. Specifically, we investigated the expression of SIRT1 and SIRT3 in the kidney, lung, skin, adipose tissue, and spleens of 6-month-old and 24-month-old mice using immunohistochemical staining. Compared with that in younger mice, the expression of SIRT1 in 24-month-old rats was increased in kidney, lung, and spleen tissue, while that of SIRT3 was decreased in adipose, kidney, and lung tissue. The results of our study suggest that aging is associated with altered patterns of expression of SIRT1 and SIRT3. In addition, we noted that the expression patterns of SIRT1 and SIRT3 varied by organ. Taken together, the results of this study suggest the possibility that SIRTs may be involved in diseases associated with aging.