Stimulation of collagen synthesis prevents the aging process. We found such a synergistic effect by using the leaves of Eucommia ulmoides Oliver, Eucomiaceae (Du-Zhong leaf) and the roots of Panax ginseng C. A. MEYER (Ginseng). The formula consists of amounts which exert no effect when used individually. We tested several formula ratios of Ginseng and Du-Zhong leaf, 1:1, 1:2, 1:3 and 1:4, and concluded that the last two formulas were effective. However, we did not observe a significant difference between 1:3 and 1:4. Thus, it was demonstrated that the formula ratio of Ginseng to Du-Zhong leaf of 1:3 was the most effective for the stimulation of collagen synthesis and the prevention of decreased protein metabolism in aging.