Abstract: Microsome antigens were extracted from homogenate of adult Schistosoma japonicum by differential centrifugation and fractionated by Sepharose CL-2B chromatography. The crude microsome antigen (JAMA-C), the urea soluble fraction (JMC) and the purified microsome antigen (JAMA) were tested with ELISA for their sensitivity and specificity in detecting schistosomal antibody. In kinetic dependent assay (K-ELISA), JAMA showed activity Of 8.8 units with homologous serum. With sera from ascariasis (3), clonorchiasis (3), paragonimiasis (3) and trichinosis (1), all the results were below 1 unit. In microtitre plate ELISA, all the three microsome antigens showed high sensitivity and specificity. The results indicated that the specific activity increased with the process of purification. In comparison with microsome antigen, the cytosol and urea soluble nucleus antigen showed lower activity. When analysed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme linked immunoelectro-transfer blot of SDS-PAGE, JAMA was shown to be a heterogenous material composed of proteins of molecular weight from 14,400 to more than 200,000 daltons and the main antigenic components were beyond 43,000 daltons.