To establish the rate of Helicobacter pylori recurrence after a standard triple-therapy regimen (bismuth subsalicylate, tetracycline, metronidazole) and determine which clinical factors affect reinfection, we prospectively followed 118 patients after successful H. pylori eradication. Elimination of H. pylori was confirmed by repeat endoscopy and urea breath test 4 wk after completion of therapy. Serial [C-13]urea breath tests were performed at 3-month intervals; antral biopsies were used to verify reinfection. Recurrence of H. pylori infection occurred in 4/118 (3.4%) patients. Three of the four relapses occurred in the lst yr after treatment. Gender, age, ethnic group, alcohol consumption, cigarette use, and gastrointestinal diagnosis do not predict H. pylori recurrence. We conclude that the rate of recurrence after successful H. pylori eradication is low, and that when reinfection takes place, it occurs most commonly within the lst yr after treatment.