Development of anti-melanogenic agents from natural sources has long been the research project of our laboratory. In this study, ethyl acetate extracts of Oreocnide fruticosa (Gaudich.) Hand.-Mazz. branches (OBE) were examined for their melanin synthesis inhibitory activities using B16 melanoma cells. Our results indicated that OBE down-regulates melanin production in a dose-dependent pattern. To clarify the target of OBE action in melanogenesis, we performed Western blotting for the key melanogenic enzymes; tyrosinase, tyrosinase related protein-1 (TRP-1) and TRP-2. The results showed that OBE efficiently inhibited tyrosinase, TRP-1 and TRP-2 in a dose-dependent manner. Therefore, OBE is a good candidate for the further study including identification of the effective chemical constituents as well as their working mechanism for the application of whitening agent in the human skin.