The aims of this study were to investigate the genotypes of hepatitis B virus and to identify the precore G1896A and basal core promoter A1762T/G1764A mutations in HBsAg and anti-HBc-positive patients. Eighty-three asymptomatic individuals, three with acute hepatitis B and 33 with chronic hepatitis B referred to viral hepatitis centers in the State of Alagoas, Brazil were analyzed according to their viral load, HBeAg/anti-HBe profile and alanine aminotransferase serum level. The genotypes identified were: A (92.5%), C (5%), D (1.25%) and F (1.25%). The precore mutation was detected in 3.8% of sequences and basal core promoter mutation in 52.4%. These were identified in 45.45% of the asymptomatic individuals and 54.55% of the patients with chronic hepatitis, irrespective of viral load and alanine aminotransferase serum level. In genotype C, only the basal core promoter mutation was identified and no mutations were identified in genotypes D and F.