Abstract: Occult hepatitis B virus （HBV） infection （OBI） is defined as the status with persistent serum HBsAg negative, but with serum/intrahepatic HBV DNA positive. Due to the differences in prevalence of HBV infection,prevalent viral strains, study samples,as well as sensitivity and specificity of methodology,the available data of OBI prevalence quite varied. The pathogenesis of OBI has not been fully elucidated. It is a complex process involving multiple virological and host factors. OBI can be transmitted through blood transfusion,parturition and liver transplantation to cause de novo infection. Immune dysfunction andapplication of immunosuppressive agents can lead to OBI reactivation and recurrence of typical serological evidence. The slight but persistent necro-inflammation can promote the progression of liver disease and increase the risk of tumorigenesis. In clinic,more sensitive detection methods are needed for diagnosis of OBI to reduce OBI-related potential threat and help clinicians to take reasonable managements to slow the progression of the disease.

Key words: Hepatitis B virus, Occult hepatitis B virus infection, Hepatitis B virus surface antigens, Hepatocellular carcinoma