Objective:To detective the expression of FasL in peripheral blood mononuclear cells(PBMC) of Chronic hepatitis B(CHB) to study the mechanism involved in peripheral blood mononuclear cell apoptosis induced by HBV. Methods: HBV DNA in peripheral blood mononuclear cells was detectived by PCR, FCM for apoptosis and western blot was used for expression of FasL in PBMC. Results: There were 24 CHB Patients with HBV DNA positive and 6 CHB patients negative in peripheral blood mononuclear cell. The apoptosis rate in positive group was (38.14±5.23)%,where negative group was (22.37±6.47)%.The expression of FasL significantly increased in positive group than negative group.Conclusion: Over-expression of FasL in PBMC of CHB maybe involved in PBMC apoptosis induced by HBV.