Sasim, a traditional prescription composed of seven herbal mixtures, has been widely used as an oriental medicine for the treatment of cerebral infarction in Korea. However, the regulatory mechanisms by which the formula affects immune processing in cerebral infarction patients remain unknown.The levels of secretory protein of tumor necrosis factor (TNF)-α were determined in both THP-1 differentiated macrophage-like (THP-1/M) cells and Peripheral blood mononuclear cells (PBMCs) from cerebral infarction patients. Also, the levels of protein and mRNA of TNF-α and heme oxygenase-1 (HO-1) were detected in THP-1/M cells under our experimental condition.Sasim markedly suppressed lipopolysaccharide (LPS)-induced TNF-α at the levels of secretory protein and mRNA in both PBMCs from cerebral infarction patients and THP-1/M cells. Interestingly, Sasim strongly induced HO-1, the rate-limiting enzyme of heme catabolism, at both the protein and mRNA levels in THP-1/M cells. Treatment with tin protoporphyrin IX (SnPP), an inhibitor of the catalytic activity of HO, significantly abolished the suppressive effect of Sasim on LPS-induced TNF-a production in THP-1/M cells.These data indicate that Sasim may be beneficial in the cessation of inflammatory processes associated with cerebral infarction through the induction of HO-1 expression.