Abstract: The fusion between myeloma cells from BALB/c mice and spleen cells of mice infected with Schistosoma japonicum has been shown to be a successful method for deriving hybridoma antibodies. Indirect immunofluorescence assay on sections of adult worm or schistosomula has successfully been used as an initial method for screening specific antibodies. Three different patterns of immunofluorescence reaction were found in the present study. Two hybrid clones have been obtained and their immunological specificities were determined. One showed positive reaction to certain body cells of the adult worm and schistosomula. Its immunoglobulin subclass was determined to be IgG1. The other showed positive reaction to the digestive tract of the adult worm but negative to schistosomula. Its immunoglobulin subclass was IgG3.