It remains unclear why the spectrum of H.pylori-related diseases differs among differentgeographic regions. We examined the non-H. pyloricontamination rates of the stomach in patients withduodenal ulcer or gastric adenocarcinoma from threedifferent regions with different spectra of H.pylori-related diseases. Gastric biopsies were culturedfrom patients with duodenal ulcer or histologicallyproven gastric cancer from Seoul, Korea; Bogota,Colombia; and Houston, Texas. The frequency of non-H.pylori contamination was tallied in relation to theclinical diagnosis. Cultures from 247 duodenal ulcer patients and 165 patients with gastric cancerhad bacterial growth. H. pylori was isolated from 207(73.7%) patients with duodenal ulcer and 90 (47.1%)patients with gastric cancer (P < 0.001). In patients with duodenal ulcer (DU) or gastriccancer (GC), the rate of positive cultures for H. pyloriwere not statistically different (P > 0.143 for DU,P > 0.190 for GC) between regions. The frequency of isolation ranged from 69% to 79% for DUpatients and from 39% to 50% for gastric cancerpatients. Non-H. pylori bacterial contamination wasfound more frequently (63%) in Colombian duodenal ulcerpatients compared to 30% ulcer patients from the UnitedStates or Korea (P < 0.001). Non-H. pylori growthoccurred in 50.8-75.5% of cancer patients and wassignificantly lower in US patients than in patients from either Colombia or Korea (P < 0.01).The geographic location as well as disease statusaffects the rate of H. pylori recovery and non-H. pyloricontamination of the stomach and may play a role in the geographic differences in manifestationof H. pylori infection. The fact that the proportion ofgastric cancer patients in the United States with non-H.pylori contamination was significantly less than that of Korea or Colombia shows that thenotion of an almost universal increase in gastricmicrobial content in gastric adenocarcinoma should bereconsidered.