Antisera prepared against histocompatibility (H-2) antigens were absorbed with erythrocyte stromata from mice of the inbred strains A (H-2a), A:SW (H-2s), BALB/c (H-2d), DBA/2 (H-2d), C3H (H-2k), C57BL (H-2b), and RFM (H-2f). Hemagglutinating antibody was eluted from the stroma of each strain with glycine-sulfate buffer. By selection of strains having different H-2 specificities, it was possible to successively remove and recover, from a multispecific starting material, antibodies having an apparently single specificity.