In order to identify antigens in circulating immune complexes (CIC) of Schistosoma japonicum, the antiserum against CIC was first successfully prepared by immunization of New Zealand rabbit with CIC isolated from schistosome-infected rabbit sera. The antigens in CIC were identified and analyzed by EITB (enzyme-linked immunoelectro-transfer blot) techniques, using the prepared antiserum against CIC, adult worm antigens (AWA), soluble egg antigens (SEA) and adult excretory antigens (ESA). The results showed that the antiserum against CIC had recognized the AWA bands of 155, 90, 70, 31/32, 20.5, 14 and 8 KD; the SEA bands of 90, 66, 46, 34.5 and 27 KD and the ESA bands of 155, 92, 87.5, 70, 60, 57.5, 50, 46, 36, 31/32, 24, 18.5, 12 and 8 KD. These findings indicate that the antigens in CIC were derived from both schistosome adult worms and eggs. In addition, the localization of the antiserum against CIC targeted antigens in adult worms was also carried out by IFAT (indirect flourescent antibody test). It is suggested that the antigens in CIC were presented mainly in the tegument and the gut of the parasite.