Aim To investigate the effects of baicalin on the expression of toll-like receptor 4(TLR4),inhibitor of κB(I-κB),and the production of tumor necrosis factor-α(TNF-α) in macrophage cells RAW264.7 induced by lipopolysaccharide(LPS).Methods RAW264.7 cells were cultured in vitro,and treated with different concentration of baicalin in the presence or absence of LPS.The mRNA and protein expression of TLR4 were determined by reverse transcription PCR and Western Blot,respectively.The expression of I-κB was detected by Western Blot.The concentrations of TNF-α in the supernatant was determined by enzyme linked immunosorbnent assay.Results LPS significantly up-regulated the expression of TLR4 and production of TNF-α in macrophage cells,and markedly inhibited the expression of I-κB.Pretreated with baicalin down-regulated LPS-induced TLR4 expression in both mRNA and protein levels,as well reduced the secretion of TNF-α.Baicalin significantly inhibited the degradation of I-κB.Conclusion Baicalin might effectively down-regulate TNF-α production in LPS-induced macrophage cells through inhibiting the expression of TLR4 and degradation of I-κB.The antiinflammation effects may be associated with the amelioration of atherosclerosis damage by baicalin.