Abstract: After the fusion of SP 2/O myeloma cells with spleen cells of BALB/C mice immunized with SEA of Schistosoma japonicum eggs, 4 cell lines of hybridoma secreting monoclonal antibodies against S. japonicum eggs have been established. Four hybridoma-derived antibodies were measured by IFA with frozen sections of adult worms and 3 different patterns of immunofluorescence reaction were clearly revealed. Of these, 3 monoclonal antibodies presented a high specificity to SEA in ELISA and also showed positive COP and IHA reaction. Another monoclonal antibody was found to be against the common antigenic determinant of Schistosoma, Paragonimus, Clonorchis in I-ELISA, The immunoglobulin subclass of the 4 monoclonal antibodies were identified as IgM.