We have previously demonstrated that dl-3n-butylphthalide (NBP) has a potential angiogenic activity. In this study, we investigated the angiogenic effect of NBP and the molecular mechanisms underlying NBP-mediated angiogenesis. Zebrafish embryos and human umbilical vein endothelial cells were treated with various doses of NBP and several signaling pathway inhibitors. NBP induced ectopic subintestinal vessel production in zebrafish embryos and induced invasion, migration, and endothelial cell tube formation of human umbilical vein endothelial cells in a dose-dependent manner. These NBP-induced angiogenic effects were partially suppressed by SU5402, a fibroblast growth factor receptor 1 inhibitor; U0126, an extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor; LY294002, a phosphatidylinositol 3-kinase inhibitor; 1L6-hydroxymethyl-chiro-inositol-2-(R)-2-O-methyl-3-O-octadecyl-sn- glycerocarbonate, an Akt inhibitor; cavtratin, an endothelial nitric oxide synthase (eNOS) inhibitor and completely inhibited by a combination of U0126 and LY294002. NBP enhanced phosphorylation of ERK1/2 and fibroblast growth factor receptor 2 expression, which were inhibited by U0126. NBP increased the phosphorylation of Akt and eNOS at serine 1177, which was blocked by LY294002. NBP-stimulated nitric oxide production, which was reduced by LY294002. Our data demonstrated that (1) NBP promoted angiogenesis and (2) the angiogenic effects of NBP were mediated by the ERK1/2 and phosphatidylinositol 3-kinase/Akt-eNOS signaling pathways. Our findings suggest that NBP could be a novel agent for therapeutic angiogenesis in ischemic diseases.