Human leukocytes express three distinct families of receptors for the Fc region of IgG (FcγR). We have prepared erythrocytes (E) coated with monoclonal anti-FcγR antibodies for the study of receptor specific phagocytosis using biotin and streptavidin. In this technique, both the E and the monoclonal antibody (mAb) are biotinylated and coupling of the mAb to the E occurs through the use of streptavidin. The same biotin/streptavidin principle was used to prepare E coated with human IgG. Using this technique, receptor specific probes or probes coated with natural ligand (IgG) can be prepared rapidly with the use of small amounts of mAb or IgG. Finally, we have used these receptor specific probes to demonstrate that all three families of FcγR (FcγRI, FcγRII and FcγRIII) expressed on human monocytes and human macrophages are phagocytic receptors. © 1992.