Rifampicin (RMP), antituberculous drug, has been controversially described for many years as an immunosuppressant. The goal of this work was to determine the influence of RMP on selected parameters of the immune response in vivo and in vitro. In vivo (in B6AF1 mice) the influence of long-term treatment on primary humoral response and cellular response was evaluated. Drug dose was 50 mg/kg. In vitro (using peripheral blood of volunteers) the influence of RMP on mitogen induced proliferation, metabolic activity of granulocytes and leukocyte induced angiogenesis by diverse subpopulation of mononuclear cells was examined. The concentrations tested were 7 and 70 micrograms/ml. RMP slightly stimulated production of anti-SRBC antibodies and suppressed cellular response in mice, decreased PHA and ConA induced proliferation in higher concentration and strongly inhibited chemiluminescence at concentration used. RMP inhibited also leukocytes induced angiogenesis.