Background As one of the intercellular adhesion molecules, CD58plays important roles in promotion of theadhesion between Tcells and target cells, hyperplasia, activation of Tcells and natural killer cells, and balancebetween Th1and Th2·We studied the relationship between the levels of CD58expression in peripheral bloodmononuclear cells (PBMCs) and severity of HBV infection·Methods The levels of CD58mRNAin PBMCs were detected using quantitative reverse transcription PCR·Thepercentage of CD58positive cells was detected by flowcytometry in patients and healthy controls·Results The levels of CD58mRNAand the percentage of CD58positive cells in patients infected with HBVweresignificantly higher than that in the control·Based on severity of HBVinfection, the patients were classified intofour groups·The expression of CD58increased significantly in an order from mild chronic, moderate chronic,severe chronic to severe hepatitis groups·The levels of CD58mRNA and the percentage of CD58positive cells inPBMCs from patients with HBV infection were both positively correlated with serum levels of ALTand AST·Conclusion The level of CD58expression is related with the severity of HBV infection and the degree of liverdamage· Background As one of the intercellular adhesion molecules, CD58plays important roles in promotion of the adhesion between Tcells and target cells, hyperplasia, activation of T cells and natural killer cells, and balance between Th1 and Th2 · We studied the relationship between the levels of CD58 expression in peripheral blood mononuclear cells (PBMCs) and severity of HBV infection · Methods The levels of CD58 mRNA in PBMCs were detected using quantitative reverse transcription PCR · The percentage of CD58 positive cells was detected by flow cytometry in patients and healthy controls · Results The levels of CD58 mRNA and the percentage of CD58 positive cells in patients infected with HBVweresignificantly higher than that in the control · based on severity of HBV infection, the patients were classified as offending groups · The expression of CD58increased significantly in an order from mild chronic, moderate chronic, severe chronic to severe hepatitis groups · The levels of CD58mRNA and the percentage of CD58posit ive cells in PBMCs from patients with HBV infection were both associated with serum levels of ALT and AST · Conclusion The level of CD58expression is related with the severity of HBV infection and the degree of liverdamage ·