The epidemiology of Helicobacter pylori infection was studied in 245 healthy children (between 3 and 20 years of age) who presented for day surgery at Arkansas Children's Hospital. H pylori infection was identified serologically using an enzyme-linked immunosorbent assay to detect the presence of IgG against the high molecular weight, cell-associated antigens of H pylori. Demographic information collected included age, gender, race, family income, type of housing, location of housing, water supply, health status, upper gastrointestinal symptoms, and keeping pets. One hundred eighty-nine white children and 56 black children were studied; 139 were boys and 106 were girls. The data were analyzed by logistic regression analysis. H pylori infection increased significantly with age (P less than .05). The frequency of H pylori infection was higher in blacks than whites (P less than .01), and this difference remained after adjusting for age, gender, and family income. Family income was used as a measure of socioeconomic class and was an important factor related to infection; the rate of acquisition of H pylori in those children with family income less than +5000/year was twice that of those with incomes greater than +75,000/year (P less than .001). There were no significant differences in H pylori infection related to gender, type of housing, location of housing, or source of water supply. It is concluded that the rate of acquisition of H pylori infection increases with age, is higher in blacks than whites, and is inversely related to socioeconomic class.