Background: The seroprevalence of antibodies against hepatitis A virus (HAV) is decreasing in many Latin American countries, along with improvements in sanitary standards. However, there is no information available about low socioeconomic status (LSE) populations. Aim: To assess the evolution of hepatitis A and E virus antibodies in a cohort of LSE Chilean children. Material and methods: One hundred sixty eight children aged four years, 97 males, coming from public primary care clinics, were studied. Two blood samples were obtained with an interval of one year. Anti-HAV and anti-hepatitis E virus (HEV) antibodies, were detected by ELISA using Abbott kits. Results: Anti-HAV was positive in 19 children (11.3%). After one year of follow-up, only 10 children had sustained reactivity (52.6%). Fourteen children, initially negative, became positive during the follow up (9.4%). Antibody titers to HAV were significantly higher in samples that remained positive, compared with those that lost reactivity. Anti-HEV was found positive in two children (1.2%). One remained positive and the other became negative. Conclusions: In this cohort of LSE Chilean children, the prevalence to antibodies against HAV and HEV is low. Follow-up detected loss of reactivity to HAV in nearly one half of the children, probably related to lower antibody levels