The aqueous extract from Asiasari radix (AEAR) was used to investigate the effect of ${alpha}$-melanocyte stimulating hormone induced melanogenesis in B16F10 mouse melnoma cells. The treatment with AEAR at the 1.0 and 2.0 mg/ml level significantly inhibited the biosynthesis of melanin without changes of cell growth and morphology compared with untreated control. The AEAR-treated cells at the 2.0 mg/ml level were more efficient than commercial arbutin at 0.1 mg/ml. The tyrosinase activity also significantly decreased in AEAR-treated cells at the 1.0 and 2.0 mg/ml level. The Western analyses confirmed the slightly decreased expression of tyrosinase by AEAR treatment. These results indicate that AEAR 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.