Abstract: On the basis of the results obtained from serological survey by GAA-IHA test among populations in eight areas with different endemicities of schistosomiasis japonica, the authors bring out three epidemiological patterns of population antibody responses to gut-associated antigen (GAA) prepared from the adult worms.It was shown that the serological results could reflect the epidemiological status indicated by other surveillance data and could provide new informations unavailable in parasitological surveys. Therefore, the serological population data can be considered as an important supplementary measure in routine surveillance for measuring the ende-micity of the disease, monitoring the changing trend of transmission of the disease, and assessing the effectiveness of a control programme in a given endemic area.