Elution of complexed immunoglobulins was carried out on renal tissue obtained at autopsy from schistosomiasis mansoni and control cases. Substantial amounts of IgG were found in acid eluates of 2 of 5 schistosomiasis cases and 2 of 3 controls. The IgG from schistosomiasis cases produced specific indirect immunofluorescence reactions in gut and tegument of sections of adult Schistosoma mansoni; no reactivity was present against egg granulomas, cercariae, or mouse liver tissue. Control case eluates produced no fluorescence with S. mansoni antigens.