Mutations in the precore and basic core promoter of hepatitis B virus (HBV) can reduce synthesis and secretion of the HBV e antigen (HBeAg) , increase viral replication, and cause HBeAg-negative chronic hepatitis B (CHB) .Therefore, these mutations are likely to have important impacts on the clinical progression of the hepatitis B disease.In this review, the recent progress in research on HBV precore and basic core promoter mutations is discussed, including but not limited to insights into the related molecular mechanisms and their biological significance for established and new laboratory tests and antiviral therapies.