The binding of four peroxidase-conjugated lectins, concanavalin A (Con-A), wheat germ agglutinin (WGA), peanut agglutinin (PNA) and soybean agglutinin (SBA), in both fixed and frozen tissue sections of human extravillous trophoblast (EVT) was determined. On the basis of its lectin binding properties the EVT cell population was found to be heterogeneous. PNA and SBA did not bind to any of the EVT cells. Con-A and WGA bound to most EVT cells, with the exception of the trophoblast of the chorion laeve. The trophoblast giant cells bound only Con-A and not WGA. The villous cytotrophoblast, from which the EVT cells are said to derive, does not express the sugar groups detected by the above lectin probes. The expression of mannosylated and di-N-acetylchitobiosyl residues by a fetally derived cell invites speculation that such expression enables it both to invade host maternal tissues and to avoid any adverse host immunological response.