Contraction forces generated by non-muscle cells, such as fibroblasts, play important roles in determining cell morphology, vasoconstriction, and/or wound healing. We have searched among various plant extracts for ingredients that generate cell contraction forces using fibroblast-populated collagen gels. Using that model, we found that an extract of horse chestnuts (Aesculus hippocastanum) is able to generate such contraction forces in fibroblasts. The involvement of stress fiber formation in that response is suggested by the inhibition of such force generation by cytochalasin D and rhodamine phalloidin stain. Clinical testing of the extract was carried out using 40 healthy female volunteers. A gel formulation that included 3% of the extract was applied topically to the skin around the eye three times daily for nine weeks. The efficacy of the extract to diminish wrinkles was evaluated by visual scoring based on photo scales. After six weeks, significant decreases in the wrinkle scores at the corners of the eye or in the lower eyelid skin were observed compared with controls. After nine weeks, similar results were obtained. Taken together, our results suggest that an extract of horse chestnuts can generate contraction forces in fibroblasts and is a potent anti-aging ingredient.