Objective To investigate the role of TLR4 in the pathogenesis of chronic hepatitis B(CHB) by study the expression of TLR4 in liver tissues in patients with CHB, and the relationship among TLR4 and serum HBV DNA level, clinical severity degrees and histo-logical grades and stages. Methods Expression of TLR4 in liver tissues was semi-quantitatively determined by immunohistochemistry and e-valuated by a scoring system in 75 patients with CHB and 10 health controls. Results The positive staining of TLR4 mainly located in the cytoplasm and some on cell membrane of bepatocytes. Expression of TLR4 in the liver tissues of patients with CHB was stronger than that of health controls. The scores of TLR4 expression in patients with mild, moderate and severe CHB were 1.0±0.5,2.3±0.5 and 2.9±0.4. The scores increased gradually and significantly along with the increase of clinical severity degrees( F = 104.8, P<0.01). The scores of TLR4 expression in the liver tissues of patients with CHB were positively correlated with the clinical severity degrees (r=0.838, P<0.01) and histological grades (r=0.579, P<0.05), but not correlated with Lg (serum HBV DNA) or histological stages. Conclusion TLR4 was up-regulated in the hepatocytes of patients with CHB. There may be a role of TLR4 in the pathogenesis of CHB.