An imported case of intestinal schistosomiasis in AIDS is analysed by the relationships between immune response, diagnostic methods, pathogenetic mechanisms. The inconclusiveness of negative results from both serology and stool parasitology is remarked whereas the efficacy of associated histological, histochemical and immunohistochemical methods is emphasized in order to get better data on aetiological diagnosis and on cell types and size of reactive granulomas. In the case studied, negative serology, absent fecal egg excretion and uneffective granulomatous response with scarcity of T and B lymphocytes have been documented by means of the above methods.