Hyperpigmentation disorders are associated with abnormal accumulation of melanin pigments, thus melanin synthesis inhibitors have been of great interest as target molecules for cosmetic and medicinal purposes. The aim of this study was to investigate the in vitro inhibitory effect of panduratin A, isolated from Kaempferia pandurata Roxb., on melanogenesis and its related enzymes such as tyrosinase, tyrosinase related protein-1 (TRP-1) and tyrosinase related protein-2 (TRP-2) in melan-a murine melanocytes. The IC50 values of panduratin A for melanogenesis and tyrosinase were 9.6 μm and 8.2 μm, respectively, while those of arbutin as a positive control were 990 μm and 660 μm, respectively. In western blot analysis, panduratin A also significantly decreased tyrosinase, TRP-1 and TRP-2 protein levels. These results indicate that panduratin A effectively inhibits melanin biosynthesis, thus creating the possibility of developing a new skin-whitening agent. Copyright © 2010 John Wiley & Sons, Ltd.