Duodenal ulcer recurrence and gastritis are reduced with successful Helicobacter pylori treatment. To identify the patient factor influencing H. pylori eradication, we prospectively evaluated 96 consecutive patients undergoing a single 2-wk course of bismuth, tetracycline, and metronidazole therapy. At the time of initial esophagogastroduodenoscopy with biopsies, each patient had a profile obtained which included demographic information, gastrointestinal pathology, and H. pylori status of the spouse. Elimination of H. pylori was confirmed by repeat esophagogastroduodenoscopy with biopsies 4 wk after the completion of therapy and serial urea breath tests. Eradication at 4 wk was successful in 80 of 96 (83%) patients. On multivariate analysis, H. pylori elimination was associated with advanced age (p = 0.002) and a greater amount of chronic inflammation on baseline antral biopsy (p = 0.024). Eradication was inversely associated with the presence of a gastric ulcer (p = 0.008) and lack of medication compliance (p = 0.030). Successful eradication reduced the severity of both acute and chronic antral mucosal inflammation. Household income, gender, ethnic group, smoking, alcohol intake, and H. pylori status of the spouse did not differ between the eradicated and noneradicated groups. We conclude that it will be important to control for influential patient factors in future studies of H. pylori treatment regimens.