It is well known that Helicobacter pylori infection is extremely common throughout the world, but most infected persons do not develop ulceration and remain asymptomatic. This study was undertaken in order to determine the prevalence of H. pylori infection, the age distribution, and the factors that may affect the frequency of H. pylori infection. We evaluated the presence of antibody against H. pylori in children and adolescents, we also assessed the efficacy of non-invasive and invasive methods for detection of H. pylori infection in children who had undergone upper gastrointestinal endoscopy. We evaluated 43 males and 18 females whose ages ranged from 1 to 17 years (mean age: 9.4 +/- 4.2). 29 of all cases were symptomatic and 32 were asymptomatic. H. pylori infection was present in 49% of the studied cases. The data were analysed by Fisher's exact chi-square and Mantel-Haenszel tests. It was found that H. pylori infection graphically increased with age in both groups from 25% at ages 3-5 to 80% at ages 16-20. But no association was determined statistically between age and H. pylori positivity (p < 0.05). H. pylori infection was determined in 14 (48%) and 16 (50%) cases in symptomatic and asymptomatic groups respectively. There was no significant difference between H. pylori and either group (p > 0.05). According to the endoscopy findings, the symptomatic group was divided into two subgroups: children with peptic ulcer and children with non-ulcer dyspepsia (NUD). An attempt was made to compare ulcer, non ulcer dyspepsia and asymptomatic cases with H. pylori positivity, but no significant relation could be established between the groups (p > 0.05). 14 (23%) of the cases had previous gastric and/or intestinal complaints in their parents (positive family history). There was a significant, statistically positive relation between family history and symptoms (p < 0.01). Nevertheless, no association was found between H. pylori infection and family history (p > 0.05). There were no significant differences in H. pylori infection related to sex, type of housing, location of housing, socio-economic status (SES) or source of water supply. It is concluded that H. pylori infection has a high prevalence in our country. Although endoscopic evaluation is an invasive method, under our conditions, histopathological examination with 97% is shown to be much more sensitive in determination of H. pylori infection. Since no community difference was determined in the prevalence of H. pylori infection, all children should be considered to be under the threat of the same risk.