One of the major functions of the immune system is anti-bacterial defence mediated among others by non-specific immunity (macrophages, granulocytes). Echinacea purpurea extracts are widely used in prophylaxis and therapy of various infections, mainly the respiratory tract, in animals and humans. The aim of this work was to evaluate the effect of prophylactic use of Echinacea purpurea extract on the development of Pseudomonas aeruginosa infection in various strains of mice and on some parameters of non-specific and also specific cellular immunity. Mice expressed various, depending on the strain used, susceptibility to infection. Echinacea feeding resulted in diminishing of bacteria number in livers of C57Bl/6 (susceptible strain) as well as B6C3F1 (relative resistant strain) mice. Echinacea feeding of the second relative resistant strain (BALB/c x C3H) F1 resulted in stimulation of granulocytes chemiluminescent and lymphocytes proliferative response.