OBJECTIVE To study anti-SIEA super-immune sera against the influence on schistosoma japonicum in vitro cultivation of newly laid eggs by adult worms, their hatches and development. METHODS The adult worm pairs of Schistosoma japonicum were collected from test animals, portae vena which infected with the worms for 38-45 days. The worm pairs were injected divided into control group with normal rabbit sera and experimental group with anti-SIEA super-immune sera. The output of newly laid eggs and the embryonic development were observed with immunofluorescence staining. RESULTS Female worms cultured in vitro with normal rabbit serum not only discharged eggs already contained in its uterus, but also produced newly formed ones. They however, did not occur in female worms cultured with anti-SIEA super-immune sera and the output of eggs by the latter was much lower than that of the former. There was also a marked decrease in the proportion of developed eggs in the experimental group compared with that in the control group. In addition, immunofluorescence staining of immature eggs and female worms by anti-SIEA super-immune sera showed that a lightened fluorescence was not only seen in the embryonic cells of immature eggs, but also in the vitelaria and in the internal membrane tissue of gut cavity of the female worms. CONCLUSIONS SIEA was possibly involved in the immunity against egg development and fecundity of schistosoma japonicum.