Helicobacter pylori are associated with chronic antral gastritis that is related to duodenal ulcer, gastric ulcer, and probably gastric adenocarcinoma. Infection of H. pylori during childhood is considered an important risk factor for gastric carcinoma in adult life. To examine the epidemiologic characteristics of H. pylori infection among schoolchildren in central Taiwan, a community-based survey was carried out using stratified sampling in 10 elementary schools and three junior high schools including students and theirs teachers. Serum specimens of 1950 healthy schoolchildren (aged 9-15 years old) and 253 teachers who were randomly sampled were screened for the H. pylori antibodies by enzyme-linked immunosorbent assay. Statistical analysis was performed by using the SPSS for Windows statistical software system. A total of 332 subjects were H. pylori antibodies positive, giving an overall prevalence of 15.1%. The age-specific seropositive rates were 11.0% in 9-12 years age group, 12.3% in 13-15 years age group, and 45.1% in the teacher group. The older the age, the higher the seroprevalence (OR = 11.53; 95% CI = 6.73-19.74; p < .001 for children vs. teachers). There was no difference in the seroprevalence of H. pylori infection by gender, ethnicity, geographical area, socioeconomic level, parental education, sibship size, family members, and source of drinking water. The teachers had a much higher prevalence of H. pylori antibodies. The finding suggests that these teachers (adults) might be infected in their early childhood and implies that the poor environmental and hygienic conditions might be responsible for it. It seemed that poor water supply system, sewage disposal, and other environmental hygiene in adult might play some roles in H. pylori infection in Taiwan (before early 1980s).