Observational, cross-sectional, populational study to determine the prevalence of infection by hepatitis B virus (HBV), hepatitis D virus (HDV), human immunodeficiency virus (HIV) and human T-lymphotropic virus type 1 and 2 (HTLV-1/2) in the Matsés ethnic group, after immunization against HBV. ELISA and qPCR tests were used in 963 residents. The prevalence of HBsAg, Anti-HBc and Anti-HBs was 3.32%, 36.03% and 58.67% respectively. In 3.1% of the population the viral load was greater than 2000 IU/mL. In children under 10 years, the prevalence of HBsAg and anti-HBc was 0.0% and 2.6%, respectively, while protective antibodies were found in 94.4%. The prevalence of HIV and HTLV-1/2 infection was 1.5% and 0.6%, respectively. It is therefore concluded that there are low rates of HBV and HDV infection in the Matsés child population. Likewise, the presence of HIV and HTLV-1/2 infection is confirmed.