Chronic hepatitis B virus (HBV) infection is a global problem and over 75% of cases are reported in the Asia Pacific region. Infection can lead to progressive liver disease, cirrhosis and hepatocellular carcinoma (HCC). Previous studies suggest the prevalence of HBV carriers in Macau to be approximately 10% of the population. This study aims to investigate the prevalence of HBV genotypes among HBV-positive teenagers in Macao and the prevalence of base core promoter (BCP) and precore (PreC) mutations in the viral genome. In addition, through monitoring aminotransferase and alpha-fetoprotein, it aims to investigate relationships among HBV genotypes, BCP/PreC mutations and HCC development. This study recruited 1991 teenagers in Macau in 2008, and the PreS1/S2, BCP and PreC region of the HBV genome from 34 HBsAg-positive subjects were amplified and sequenced to determine HBV genotype and presence of HCC-associated mutations. Results suggested that the average rate of HBV infection among secondary school teenagers in Macao is low, and HBV genotype B and C viruses were found to predominate in Macao. The BCP/PreC mutations A1762T, G1764A, G1896A and C1766T were identified in 2.9-11.7% of subjects. However, no significant relationship was observed between HBV genotype, BCP/PreC mutations and HCC development.