E. histolytica tissue invasion induces IgG and IgM and probably IgA serum antibody formation of different types in the intestinal mucosa. 21 children with intestinal invasive amebiasis were studied. Samples were taken from peripheral blood and stools during diagnostic studies and three weeks later. Contraimmunoelectrophoretic antibody determinations and indirect hemagglutination tests IH were made in an attempt to demonstrate its true nature. During the acute phase (first sample), results showed antibodies against amoeba in stools by CIE in 57 per cent and by IH in 80 per cent; in serum, results were 38 and 76 per cent respectively. In the second sample and three weeks after diagnosis was established a decrease in the number of patients with coproantibodies against amoeba was observed and the number of patients with serum antibodies increased. We are also providing evidence that supports the IgG and IgA nature of coproantibodies against amoeba. These results suggest the presence of a local immunological reaction in invasive amebiasis.