Asiatic acid, madecassic acid, and asiaticoside, terpenoids with an ursane skeleton, were tested separately and in combination on skin human fibroblast collagen I synthesis in vitro. In the absence of ascorbic acid, the mixture as well as each individual component stimulated collagen I synthesis to a similar extent. In the presence of ascorbic acid, the level of collagen I secretion was higher for each individual component and for the mixture. A comparison of asiaticoside and asiatic acid shows that the sugar moiety of the molecule does not seem to be necessary for this biological activity.