This report describes the production and characterization of five murine monoclonal antibodies that react with granule proteins of human granulocytes. Monoclonal antibody AHN-11 (IgG2) reacted specifically with neutrophil cathepsin G; no reactivity with the homologous neutrophil neutral proteases, elastase, proteinase 3, or esterase N was detected. Antibodies AHN-9 (IgG1) and AHN-9.1 (IgG2b) each reacted with different epitopes on human lactoferrin, but now with the homologous protein transferrin. Two IgG1 antibodies, AHE-1 and AHE-2, reacted specifically with eosinophils; AHE-1 reacted strongly with eosinophil peroxidase but not eosinophil major basic protein while AHE-2 recognized eosinophil major basic protein but not eosinophil peroxidase. All five antibodies could detect their respective antigens in alcohol-fixed cytospin preparations. These antibodies should be useful for immunolocalization and quantification of their respective antigens as well as for other studies of the roles of these proteins in granulocyte function and differentiation.