Abstract : Africa bears a disproportionate share of the global hepatitis burden. The Comoros are classified among the countries with intermediate prevalence of hepatitis B virus (HBV) infection. The aim of this study was to determine the diagnostic circumstances and the genotypes of circulating HBV among HBV-infected patients on the island of Ngazidja, Comoros. Genotyping was performed using specific primers in multiplex PCR (Polymerase Chain Reaction) targeting the S region. 60 patients with chronic hepatitis B were included in the study, comprising forty chronic patients and thirty randomly selected samples from in the medical biology laboratory of Elmaarouf National Hospital Center (CHN) in Moroni. The average age of the patients in this study was 34.4 years. The circumstances of HBV diagnosis were primarily related to transmission prevention, notably through blood donations and prenatal screening. Genotype distribution revealed a predominance of genotype D (100%) patients and 1 patient presented with a co-infection of genotypes D and E. This study underscores the importance of monitoring medical practices that risk HBV transmission and shows that genotype D predominates among patients on the island of Ngazidja. Further research is needed to enhance prevention and treatment strategies.