We report an antibody (anti-MINY) that recognises a novel low-incidence MNS-related blood group antigen. Anti-MINY agglutinates all Hil-positive red cells tested (Mi.III, Mi.V, Mi.VI, GP.Kipp, GP.Mor and AG) and Hil-negative TSEN-positive red cells (Mi.IV, JR, JL, Oca. and Rag.). All MINY-positive red cells possess glycophorin A-B hybrid molecules. The MINY antigen occurs at the unique amino acid sequence which results from the junction of glycophorin A58 to glycophorin B27 regardless of whether the glycophorin B gene encodes methionine or threonine at amino acid residue 29 of normal glycophorin B. The MINY antigen has been provisionally assigned the MNS blood group system number 002.034 on behalf of the ISBT Working Party on Terminology for Red Cell Surface Antigens.