Peripheral blood lymphocytes from two polytransfused renal dialysis patients were transformed by Epstein Barr virus, fused to heteromyeloma and cloned. Eight human monoclonal antibodies from the resulting clones were tested for their binding to variety of antigens by ELISA, indirect immunofluorescence and immunoblotting. Antigens tested included B‐cell lines, T and B lymphocytes, red blood cells, chronic lymphocytic leukaemic B cells, IgG, ssDNA, dsDNA. histones, nucleoprotamine, sperm nuclei, thymus and spleen extracts. MOLT4 cell lysatcs, affinity purified autoantigens, tetanus toxoid, bacterial lipopolysaccharide, insulin, and tissue section screen. These human monoclonal antibodies reacted with more than one antigen to varying degrees and were autoreactive and pulyreactive. One of these heterohybridoma cell lines exhibited cytoplasmic staining with an anti‐CD5 monoclonal. Our findings support the concept that in adult individuals subset of B cells produce heterogeneous IgM antibodies which can bind to variety of different autoantigens and also to foreign antigens. These monoclonals were different from the autoantibodies usually seen in renal dialysis patients in the sense that they were not lymphocytoto