The endothelium of blood vessels plays a significant role in the regulation of normal and pathological processes occurring in the tissues. Monoclonal antibodies (MAbs) against endoglin (CD105), a marker of endothelial cells, are considered as potential agents to affect the functional characteristics of endothelial cells. The purpose of the study was to assess the in vitro ability of MAbs against different endoglin epitopes to modify the functional characteristics of human endothelial cells of EA.hy926 line. We found that different MAbs can slow down cell proliferation or migration, increase the adhesion of monocyte-like cells, or diminish the rate of soluble endoglin accumulation in a growth medium. Two of the eight studied MAbs were able to affect several functional properties of endothelial cells.