Compound K (CK; 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol), an active ginseng saponin metabolite, exerts anticancer activity via apoptosis induction in various cancers. In the present study, we investigated the anti-angiogenic activity of CK and its molecular mechanisms in human umbilical vein endothelial cells (HUVECs). Angiogenesis was induced in HUVECS by basic fibroblast growth factor (bFGF), a potent angiogenic growth factor. CK significantly inhibited the proliferation and also attenuated the expression of a proliferating protein cyclin D1 in bFGF treated HUVECs. Also, CK significantly inhibited the migration and tube formation of bFGF treated HUVECs at non-cytotoxic concentrations, reduced secreted level of vascular endothelial growth factor (VEGF) and increased the secreted level of pigment epithelium-derived factor (PEDF) in HUVECs. In addition, CK effectively disrupted bFGF-induced neo-vascularization in the Matrigel plugs excised from mice in vivo. Notably, we have found that CK downregulated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and AKT in bFGF treated HUVECs. Taken together, our findings for the first time indicate that CK exerts anti-angiogenic activity via inhibition of p38 MAPK and AKT in HUVECs with the potential of a cancer chemopreventive agent.