ObjectiveTo study the hepatitis B virus basic core promoter (BCP) mutation in HBV infected patients.MethodsThe serum samples from 132 HBV infected patients (all were HBV DNA positive) were collected. The gene covered HBV BCP were amplified by nested polymerase chain reaction (nPCR). The PCR products were sequenced directly, and the mutations in BCP T1762/A1764 were determined by sequence analysis. HBV genotypes were also detected by restriction fragment length polymorphism based on S gene PCR products.ResultsThe mutation rates of BCP T1762/A1764 were 27.45 % in 51 cases of HBV infected patients with HBeAg(+)，62.96% in 81 cases of HBV infected patients with HBeAg(-). The mutation of patients with HBeAg(-)was significantly higher than those with HBeAg(+)（χ2=15.79, P=0.00）.The detection rate of B gene mutation of BCP T1762/A1764 in HBV infected patients was 33.85%, which was obviously lower than 66.15% of C gene mutation (χ2=24.25, P=0.00）.ConclusionThe mutation in BCP T1762/A1764 generally exist in HBV infected patients and common in genotype C.