Abstract: The authors used sensitized lypholized Schistosoma japonicum egg antigen in indirect haemoagglutination test for the diagnosis of schistosomiasis japonica. Human O group erythrocytes are fixed with glutaraldehyde, tanned with tannic acid, sensitized with S. japonicum egg antigen and lypholized. IHA test using the antigen recommended by the author was carried out in several provinces during the past nine years. A qualitative comparison of IHA test with faecal examination technique in 4,835 proven cases with schistosomiasis showed a high agreement, i.e., 91.9-100%. It is suggested that IHA test using this antigen is easy to handle and specific and sensitive enough to be employed for serodiagnosis of schistosomiasis.