Abstract: Endoglin, a co-receptor of TGF-β family growth factors, is an endothelial cells marker. In our previous work we have demonstrated that monoclonal antibodies (MABs) against endoglin can change the functional properties of endothelial cells EA.hy926. The aim of the present work was to study the effects of these antibodies on HUVEC endothelial cells, as well as to correlate the data obtained for HUVEC and EA.hy926 cells. Comparison of in vitro models based on the permanent EA.hy926 endothelial cell line and primary HUVECs revealed, along with common morpho-functional properties, a number of dissimilarities in the le-vels of adhesion molecules and the expression of endothelial differentiation genes. Anti-endoglin MABs 2C8 and 4E4 inhibited HUVEC cells migration, reduced their adhesion to solid substrate, influenced the arrangement of actin microfilaments, and impeded the formation of caspillary-like structures. These effects were revealed either in presence of TGF-β1 in culture medium or under hypoxia. Supplementation of the growth medium with MABs 2C8 promoted endoglin shedding from HUVEC membrane both in hypoxia and normoxia. Several impacts of anti-endoglin MABs on HUVEC cultures were similar to those detected on EA.hy926 cells. However the effect of MABs 2C8 on endoglin shedding by HUVEC and EA.hy926 cells was opposite.