The antibody response of the appropriate hosts (cattle) to Taenia saginata larvae was compared with that of an inappropriate host (Balb/c mice) using gel electrophoresis followed by immunoelectrotransfer blot techniques (Western blotting). Three groups of cattle were included, those known to be resistant to challenge infection because of repeated oral challenge with T. saginata eggs over a 1-year period, a previously infected but known susceptible group and a group of uninfected controls. Serum from the mice and the two groups of infected cattle contained antibodies recognizing different 'target' antigens, some of which may be related to host resistance. The potential value of the technique of Western blotting in dissecting the humoral response of a particular host species to parasitic infection and in the identification of those antigens suitable for the production of effective vaccines is discussed.