The effect of feeding mice Rhodiola quadrifida aqueous (RQW) and 50% hydro-alcoholic (RQA) extracts on Pseudomonas aeruginosa infection was studied. It was found that the infection intensity was significantly lower, in comparison to the control, when mice obtained daily, for 7 days before P. aeruginosa and Pseudomonas inoculation, 0.4 mg of RQA extract. In contrast, no difference was observed between the number of bacteria in livers of mice fed RQW extract and mice belonging to the control group. Both lymphocytes and granulocytes numbers in the blood collected from mice fed RQW extract were significantly lower than in the respective controls. Mice fed higher RQA dose presented more lymphocytes in their blood than their corresponding controls, and no differences in granulocytes level. There were no effect of both extracts on anti-sheep red blood cells (SRBC) antibody production in lower 0.04 dose, in higher dose (0.2 mg) aqueous (RQW) extract diminished anti-SRBC antibody response.