Goal: To find out the role of family members in the Helicobacter pylori infection in childhood by investigating the incidence of infection within families of H. pylori-infected children. Background: H. pylori infection is usually acquired in early childhood and possibly family members are the main source of infection. Study: One hundred consecutive children with upper gastrointestinal symptoms, without previous H. pylori eradication treatment were prospectively studied by gastroscopy and C-13-urea breath test. Simultaneously, all family members were studied by C-13-urea breath test regardless of earlier eradication treatment for H. pylori infection. The age of children and their parents, socioeconomic status, parents' education, and living conditions were recorded. Results: Forty-four index symptomatic children were infected by H. pylori. No statistical difference was found concerning demographic factors, between H. pylori-positive and H. pylori-negative index children except age, which was higher in the H. pylori-infected children (P = 0.009). In all H. pylori-positive and in 71.4% of the negative index children. at least I more family member was infected (P < 0.001). always including a parent in the H. pylori-positive, compared with 69.6%) in the H. pylori-negative group (P < 0.001). The percentage of infected siblings, mothers and fathers was higher in H. pylori-infected index children (P < 0.001, P = 0.001, and P = 0.035, respectively). Conclusions: The prevalence of H. pylori infection is significantly higher among families of infected index children. The presence of at least I infected family member in all H. pylori-positive index children suggests that the family could be the main source of H. pylori infection in children.