The aim of the work was to investigate breed differences in cellular immune response to simultaneous immunization with Ultra-corn and Covexin-8, and its relation to disease resistance. Finnish Landrace and Rahmani lambs, as well as 12, 74 and 3/8 F Rfl lambs were included in this trial. All lambs used responded well to Ultra-corn and multivalent clostridial vaccines, as
 indicated by the increased values of total leucocytic counts, lymphocytes, monocytes, erythrocyte rosette forming lymphocytes, and skin delayed type hypersensitivity. The crossbreds / FRF2 and 14 FRF2 lambs were shown to have an efficiently stimulated cell mediated immune response as recognized for the local Rahmani lambs while 3/8 FR and the foreign breed Finn lambs showed the lowest response.