Biological aging (BA) is a comprehensive assessment tool for elderly persons. The authors aimed to develop a rat model that can be used to assess BA by evaluating various blood, biochemical, and hormonal parameters and demonstrate that the intravenous administration of autologous adipose-derived stem cells (ADSCs) improves BA. Twelve elderly (aged 20 months) male Sprague-Dawley rats were used in this study and divided into 2 groups: autologous ADSC administration (n = 6) and saline administration (n = 6). The complete blood count, biochemical and hormonal parameters, and antioxidant potential were evaluated before harvesting the rat inguinal fat tissue and intravenous ADSC administration as well as at 1, 3, and 5 weeks after ADSC administration. Adipose-derived stem cells administration regulated blood content, biochemical parameters, renal function, and antioxidant enzymes in elderly rats. Furthermore, changes in several hormonal levels were identified in the ADSC administration group compared with the saline administration group. An assessment model of BA in elderly rats was successfully developed after the intravenous administration of autologous ADSCs. The authors suggest that intravenously injected ADSC treatment may be a valuable method to improve BA.