To develope skin-whitening or therapeutic agents against hyperpigmentation, aqueous extract from Amomum xanthioides (AEAX) was evaluated for melanogenesis inhibitory activity in B16F10 melanoma cell. The treatment with AEAX at the 0.5 and 1.0 mg/ml level significantly inhibits the biosynthesis of melanin compared with untreated control. The AEAX-treated cells at the 1.0 mg/ml level were more efficient than commercial arbutin at 0.1 mg/ml. The tyrosinase activity also significantly decreased in AEAX-treated cells at the 0.5 and 1.0 mg/ml level. The Western analyses confirmed the significantly decreased expression of tyrosinase and tyrosinase-related protein-1 by AEAX treatment. These results indicate that AEAX may contribute to the inhibition of melanin biosynthesis through regulating tyrosinase activity and expression and serve as a new candidate in the design of new skin-whitening or therapeutic agents.