Abstract: The effects of tetrandrine (Tet) on the expression of cyclooxygenase-2 (COX-2),prostaglandin E₂ (PGE₂),inducible isoforms of nitric oxide synthetase (iNOS) and nitric oxide (NO) in LPS-stimulated RAW264.7 cells were investigated.RAW 264.7 cells were pretreated with LPS 1 μg/mL to set up the cell inflammatory model;various concentrations (1×10^-8,1×10^-7,1×10^-6 mol/L)of Tet were administered to explore its effect on the expression of COX-2/PGE₂,iNOS/NO in these LPS-stimulated cells.Western blotting was applied to detect the expression of intracellular COX-2 and iNOS;special NO kit was used to detect the level of NO,and enzyme immunoassay (EIA) kit to that of PGE₂.The results showed that Tet significantly decreased the expression of PGE₂ and NO as well as COX-2 and iNOS synthetase in LPS-stimulated RAW264.7 cells in a dose-dependent manner.So it suggests that Tet can inhibit the inflammation response in LPS-stimulated RAW264.7 cell,which might be mediated by down-regulating the expression of PGE₂and NO through the inhibition of COX-2 and iNOS synthetase.