en Internal Medicine Internal Medicine Original Research Original Research Seroepidemiologic studies in developing countries show a high rate of Helicobacter pylori (H. pylori) infections in children, in contrast to developed countries. The aim of this study was to evaluate the prevalence of H. pylori in children and teenagers in Tabriz, northwest of Iran. In this prospective study 44 children and teenagers were randomly selected to study serum IgG against H. pylori using ELISA method. Our results indicated the presence of IgG in 83.5% of test subjects (83.7% in females and 83.4% in males). In the 2-5 years age group 71.7% were IgG positive and this percentage increased by age, i.e., 95.2% recorded as IgG positive in the 14-18 years age group (p<O.05). Considering the risk factors in relation to H. pylori infection, an increasing number of family members (above 3 persons) showed a statistically significant difference (p<O.05), while other factors such as economical situation of the family, educational level of parents and lack of a private room for children in the family didn't show significant differences (p>O.05). In general, our findings indicate that the prevalence of H. pylori in Tabriz, like other developing countries is high from early age and increases further by age. More studies are needed to clarify the reasons for this high prevalence. H. pylori, Seroepidemiology, Children, Teenager. 19 23 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-227&slc_lang=en&sid=1 E FATTAHI 20031947532846006798 20031947532846006798 Yes From the Departments of Internal Medicine, Immunology and Physiology, Medical School, Tabriz University of Medical Sciences, Tabriz, l.R. Iran. B RAHNEMA 20031947532846006799 20031947532846006799 No N GANDCHILAR 20031947532846006800 20031947532846006800 No