Objective To investigate the effect of endothelial microparticles (EMPs) on monocytes in promoting inflammatory angiogenesis and in expressing endothelial markers. Methods EMPs were isolated from the supernatants of cultured human umbilical vein endothelial cells (HUVECs) treated with TNF-αby ultracentrifugation, identified under an electron microscope and applied to cultured THP-1 cells. The level of VEGF-A and VEGF-C expressed by THP-1 cells was examined with ELISA. The expression of von Willebrand factor (vWF) and vascular endothelial growth factor receptor 2 (VEGFR-2) in THP-1 cells were studied with RT-PCR and immunofluorescence. HUVECs were co-cultured with THP-1 cells either treated with EMPs not. The proliferation of HUVECs was assessed. Results TNF-α enhanced HUVECs to release EMPs, which promoted THP-1 cells to secrete vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor C (VEGF-C). THP-1 cells did not express vWF or VEGFR-2 genetically after either 3 days or 8 days of culture. When cultured with THP-1 cells, HUVECs were more active in proliferation. Conclusion EMPs are able to activate monocytes which in turn enhanced endothelial cells growth by secreting