Abstract: Pathological changes and immune complex deposits in the kidneys of mice infected With Schistosoma japonicum were studied from 18 days to 5 months post infection and after treatment.In immunofluorescent preparations, deposits of small amounts of IgG and C3 followed by IgM in glomerulus appeared on day 18-25 after infection, with increasing in tensicy from day 40 till the end of the second month after infection. No schistosome antigen could be found on frozen sections of kidneys by indirect fluorescent test.Pathological observation revealed that from the fourth week to two months after infection a large number of glomeruli were affected, showing diffuse hyper-cellular enlargement of Bowman's capsule and thickening of glomerular capillary wall. Granular casts were also found in some of the tubules.Electron microscopic studies have shown the presence of pigment deposits and electron-Cense deposits resembling the humps along the thickened basement membrane, suggesting that the glomerular lesions corresponded quite closely to the immune complex deposits. After treatment most of the lesions disappeared within 2 months.