With the use of the cytochemical stain for horseradish peroxidase of Graham and Karnovsky (1966. J. Histochem. Cytochem. 14:291), conjugates of horseradish peroxidase with ricin, wheat germ agglutinin, and phytohemagglutinin were employed for the morphologic demonstration of d-galactose (ricin), N-acetylglucosamine (wheat germ), and N-acetylgalactosamine (phytohemagglutinin) containing moieties on the surface of unfixed, or paraformaldehyde-fixed rat lymphoid cells. D-Galactose, or d-galactose containing disaccharides inhibited the interaction between ricin peroxidase and lymphoid cell surface; also, N-acetylglucosamine inhibited the wheat germ peroxidase-lymphoid cell interaction, but N-acetylgalactosamine failed to inhibit the reaction between phytohemagglutinin peroxidase and the surface of lymphoid cells.