Galectin-1 (gal-1), a member of the mammalian β-galactoside-binding proteins, recognizes preferentially Galβ1-4GlcNAc sequences of several cell surface oligosaccharides. We demonstrate histochemically that the lectin recognizes appropriate glycotopes on the syncytiotrophoblast and extravillous trophoblast layer from second trimester human placenta and on BeWo chorion carcinoma cells. Gal-1 binding to BeWo cells was diminished by the Thomsen–Friedreich (TF)-disaccharide (Galβ1-3GalNAc-) conjugated to polyacrylamide (TF–PAA). Gal-1 also inhibited BeWo cell proliferation in a concentration-dependent manner. Similar antiproliferative effects were also observed with an anti-TF monoclonal antibody (mAb, A78-G/A7). Therefore, we conclude that ligation of Galβ1-4GlcNAc and Galβ1-3GalNAc epitopes on BeWo cells may have regulatory effects on cell proliferation.