Abstract: Two IgM isotype monoclonal antibodies(McAb),2H10 and 2H1,recognizing repetitive epitopes on Schistosoma egg associated molecules were characterized and their specificities were identified in a two site sandwich ELISA system.In consistent with the differences in immunological behaviour and specificity demonstrated with immunoelectrophoresis(IEP) and immunofluorescent antibody(IFA) techniques,absolutely negative reactions found in the he terologous detecting system with alternated capture and detecting McAbs of the two revealed a complete incompatibility giving evidences that epitopes on different molecules were recognized.Immunological liability of the target antigen SEA or SEA TCA to the two McAbs were demonstrated on sodium periodate and trifluoroacetic acid treatment indicating the biochemical nature of these epitopes were glycosyolated molecules with apparently higher resistance to the oxidizing agent showing in 2H10 recognizing epitopes. By means of an ion gradient Mono Q FPLC system (Pharmacia),2H10 reactive epitopes of SEA,being tested not so efficiently adsorbed by ConA sepharose affinity column,was found successfully concentrated in the profile eluted with pH 8.0 PBS at 0.2 0.4 NaCl ionic strength. Repeated trials on SDS PAGE and Western blotting analysis with the reactive fractions further showed a heterogeneity of molecular weight range as well as the non transferable property of the CHO reactive groups.