Studies of anti-S. mansoni immunological responses in individuals living in endemic areas identified immunogens (Sm37-GAPDH and Sm10-DLC) with vaccine candidate properties. Analysis of the epitopes of these immunogens indicated that: (i) Sm37-5 is a major B-cell epitope of Sm37-GAPDH and the IgG antibody reactivity toward this determinant is associated with resistance to reinfection; (ii) Sm10-T is a T-cell epitope of the major T-cell immunogen Sm10-DLC. This led us to test a multiple antigen peptide (MAP) containing Sm37-5 and Sm10-T as an anti-schistosome vaccine. This MAP induced a significant protective immune response in mice when injected in Freund's adjuvant or coadsorbed with GM-CSF on aluminium hydroxide. In the latter case the physical link between the cytokine and the antigen via the coadsorption on alum was necessary to obtain a protective response. Results of the antibody response indicated that when the MAP and GM-CSF were coadsorbed on alum, the antibody response against the Sm10-T epitope located in the NH 2 -terminal position was significantly amplified up to 30% of the anti-Sm37-5 response.