Abstract: AimTo investigate the inhibitory effects of artesunate on angiogenesis. MethodsThe in vitro anti-angiogenic effect of artesunate was tested on models of angiogenesis: proliferation, migration and tube formation of human umbilical vein endothelial (HUVE) cells; The anti-angiogenic effect in vivo was evaluated in nude mice by means of human ovarian cancer HO-8910 implantation and immunohistochemical stainings for microvessel (CD₃₁), vascular endothelial growth factor (VEGF) and VEGF receptor KDR/flk-1. Results Artesunate significantly inhibited angiogenesis in a concentration-dependent form in range of 0.5-50 μmol·L^-1. The IC₅₀ of artesunate for HUVE cells was (21±3) μmol·L^-1. Growth of xenograft tumor was decreased and microvessel density was reduced following drug-treatment with no apparent toxicity to the animals. Artesunate also remarkably lowered VEGF expression on tumor cells and KDR/flk-1 expression on endothelial cells as well as tumor cells. ConclusionArtesunate was shown to inhibit angiogenesis in vitro and in vivo. These findings together with the known low toxicity of artesunate are clues that artesunate may be a promising angiogenesis inhibitor.