Abstract: The endothelium of blood vessels plays an important role in the regulation of normal and pathological processes occurring in the tissues. Monoclonal antibodies (MAbs) to endoglin (CD105), a marker of endothelial cells, are considered as potential agents to affect the functional characteristics of endothelial cells. Here, we report the ability of MAbs against several epitopes of endoglin to modify the functional characte-ristics of human EA.hy926 endothelial cells in vitro. Different MAbs were found to slow down cell proliferation or migration, to increase the adhesion of monocyte-like cells, or to reduce the rate of soluble endoglin accumulation in a culture medium. Two MAbs of the eight studied reagents were able to affect several functional characteristics of endothelial cells.