A 73% prevalence of Helicobacter pylori infection was estimated in adults in the 2003 Chilean National Health Survey. However, this infection is usually acquired during childhood. To determine the frequency of H. pylori infection in healthy Chilean children from a school in Santiago. A cross sectional study in a private/ subsidized school in Santiago. Children aged less than 18 years were invited to participate. The parents of those who accepted answered a demographic survey and a stool sample was obtained from participants to detect H. pylori antigen using a monoclonal antibody ELISA kit. We studied 144 students aged 10.6 ± 3.1 years (54% females). Twenty six participants (18.1%, 95% CI: 12.4-24.9%) had a positive test. Children from higher socioeconomic levels had a non-significant lower frequency of infection. No differences in the frequency of infection were observed by age, gender, household type or number of people living in it or history of breastfeeding. In this sample of children, an 18.1% frequency of H. pylori infection was observed.