We have previously reported that salmosin, a novel disintegrin, was isolated from Korean snake (Agkistrodon halys brevicaudus) venom and significantly inhibited solid tumor growth in mice by perturbation of tumor-specific angiogenesis via blocking alpha nu beta 3 integrin expressed on vascular endothelial cells. In this study, we investigated the functional specificity of salmosin in tumor cell metastasis. Recombinant salmosin expressed in E. colt that has the RGD sequence markedly inhibited both B16F10 melanoma cell adhesion to the extracellular matrix proteins as well as B16F10 melanoma cell invasion through Matrigel-coated filter. The inhibition by salmosin can be caused by blocking integrins expressed on the surface of B16F10 melanoma cells. Salmosin significantly inhibited the proliferation of B16F10 melanoma cells on the plate coated with collagen I in a dose-dependent manner. In vivo B16F10 melanoma experimental metastasis, salmosin showed remarkable significant inhibitory effect on lung tumor colonization in a concentration-dependent manner. These results clearly demonstrate that antimetastatic activity of salmosin resulted from blocking the integrin-mediated adherence and alpha nu beta 3 integrin-mediated proliferation of the melanoma cells.