A modified urease broth test was used in 109 gastric biopsy specimens of children that yielded a 96% sensitivity and a 100% specificity rate for Campylobacter pylori infection. The longest reaction time was less than or equal to 4 min. The correlation between the degree of C. pylori infection and the reaction time was found to be highly significant (gamma = 0.78, p less than 0.001). Patients were examined as outpatients, and immediate medications were prescribed for eradication of the bacteria on the basis of the urease broth test results. This is the first report on the use of this modified rapid urease test for the diagnosis of C. pylori infection in children.