The presence of common antigens (Ag) between Fasciola gigantica and Lymnaea natalensis was demonstrated. Two different groups of mice were immunized with: crude somatic extract of L. natalensis and redia of F. gigantica. The mice's polyclonal antibodies (Ab) were evaluated by ELISA and immunoblotting. Both extracts were immunogenic in mice according to these two techniques, when evaluated against the homologous Ag. From 11 to 13 bands were identified in L. natalensis and from 9 to10 bands were recorded in redia Ag by the autologous sera. Cross-reactions between F. gigantica and L.natalensis were found by ELISA and immunoblotting. Anti-F. gigantica Ab recognized 10 components in snail crude extract. Likewise, immune sera against snail extract identified eleven bands in redia Ag. This is the first work that demonstrates the shared Ag between redia of F. gigantica and L. natalensis. From this finding it may be concluded that L. natalensis constitutes a rich source of Ag for serodiagnostic and prophylacticstudies for F. gigantica. The snail antigen (SAg) is easy to obtain, with a high recovery of proteins and low cost, compared to other parasite Ag.