Objective:To investigate the relation between hepatitis B virus(HBV) genotypes and the double mutation of A-to-T nucleotide(nt) 1762 and G-to-A nt 1764 in basic core promoter(BCP T1762/A1764) in patients of the Li nationality. Methods:Subjects were 125 HBV DNA positive patients that belong to the Li nationality on Hainan Island. HBV DNA genotype was determined by real time fluorimetry polymerase chain reaction. BCP T1762/A1764 mutation was performed using the direct sequencing method. Results:The prevalence rates of genotype B, genotype C, genotype D, genotype C and D mixed infection(genotype C + D) and genotype B and D mixed infection (genotype B + C) were 31.20%, 53.60%, 12.00%, 2.40% and 0.80% respectively. Mutation frequencies in patients infected with HBV genotype C(58.21%) were significantly higher than in those infected with other genotypes (P <0.01). The serum viral load of the patients with genotype C(5.74±1.21) was also higher than that of those with genotype B(P <0.01). Conclusion:The major genotypes in the Li nationality were genotype C and genotype B. The infection of genotype D and mixed infection also occurred in the Li nationality. Genotype C HBV has a higher replication rate, and the different degrees of pathogenecity among HBV genotypes may be related to BCP T1762/ A1764 mutation frequency. Objective: To investigate the relation between hepatitis B virus (HBV) genotypes and the double mutation of A-to-T nucleotide (nt) 1762 and G-to-A nt 1764 in basic core promoter (BCP T1762 / A1764) in patients of the Li nationality. Methods: Subjects were 125 HBV DNA positive patients that belong to the Li nationality on Hainan Island. HBV DNA genotype was determined by real time fluorimetry polymerase chain reaction. BCP T1762 / A1764 mutation was performed using the direct sequencing method. : The prevalence rates of genotype B, genotype C, genotype D, genotype C and D mixed infection (genotype C + D) and genotype B and D mixed infection (genotype B + C) were 31.20%, 53.60%, 12.00%, 2.40 % and 0.80% respectively. Mutation frequencies in patients infected with HBV genotype C (58.21%) were significantly higher than those infected with other genotypes (P <0.01). The serum viral load of the patients with genotype C (5.74 ± 1.21) was also higher than that of those with genotype B (P <0.01). Con clusion: The major genotypes in the Li nationality were genotype C and genotype B. The infection of genotype D and mixed infection also occurred in the Li nationality. Genotype C HBV has a higher replication rate, and the different degrees of pathogenecity among HBV genotypes may be related to BCP T1762 / A1764 mutation frequency.