Eight antigen preparations of schistosama japonicum. i. e. freezethawed antigens (FFT, F-MFT), saline-extract antigens (FE. F-ME, ME) SEA and AWA, were separated by SDS-PAGE. The results showed different fractional proteins among the eight antigens. These above mentioned antigens were used to detect sera from patients of different stages of schis-tosomiasis by means of ELIB. It demonstrated that the defined .fractional proteins below 60KD could be recognized by sera from acute schistosomiasis, the defined fractional proteins over 60KD recognized preferentially by sera from advanced schistosomiasis, while the fractional proteins of 87KD, 70KD, 60KD, 31KD and 18KD of S. japanicum antigens could be recognized by almost all sera from patients of different stages.