Purpose: This study was performed to determine the inhibitory effect of Sihosogansangagambang (SS) on melanin synthesis in B16F10 melanoma cells (B16F10). Methods: The inhibitory effects of Sihosogansangagambang on melanin synthesis were used by in vitro assay. To elucidate inhibitory effects of SS on melanin synthesis, we determined the melanin release in B16F10. And to investigate the mechanism of inhibitory effect of SS, we assessed the gene expression of tyrosinase, TRP-1, TRP-2 and ERK-1 in B16F10. Results: 1. SS decreased the release of melanin in B16F10 melanoma cells. 2. SS inhibited mushroom tyrosinase activity in vitro. 3. SS decreased the expression of tyrosinase, TRP-2 in B16F10 melanoma cells, but did not decreased the expression of TRP-1 in B16F10 melanoma cells. 4. SS decreased the expression of ERK-1 in B16F10 melanoma cells. Conclusion: From these results, it may be suggested that SS is possesed of the antimelanogenetic effects.