Bibenzyl is a type of active compounds abundant in Dendrobium. In the present study, we investigated the inhibitory effects of six bibenzyls isolated from Dendrobium species on vascular endothelial growth factor (VEGF)-induced tube formation in human umbilical vascular endothelial cells (HUVECs). All those bibenzyls inhibited VEGF-induced tube formation at 10 micromol x L(-1) except tristin, and of which moscatilin was found to have the strongest activity at the same concentration. The lowest effective concentration of moscatilin was 1 micromol x L(-1). Further results showed that moscatilin inhibited VEGF-induced capillary-like tube formation on HUVECs in a concentration-dependent manner. Western blotting results showed that moscatilin also inhibited VEGF-induced phosphorylation of VEGFR2 (Flk-1/KDR) and extracellular signal-regulated kinase 1/2 (ERK1/2). Further results showed that moscatilin inhibited VEGF-induced activation of c-Raf and MEK1/2, which are both upstream signals of ERK1/2. Taken together, results presented here demonstrated that moscatilin inhibited angiogenesis via blocking the activation of VEGFR2 (Flk-1/KDR) and c-Raf-MEK1/2-ERK1/2 signals.