A prospective study of infection due to Helicobacter pylori in 104 Southern Appalachian veterans with upper gastrointestinal symptoms revealed a prevalence of 67%. There was no age difference observed between those with and without H pylori. The organism was shown to be present in 12 of 13 patients with duodenal ulcer (92%), 6 of 10 with gastric ulcer (60%), and 52 of 81 with nonulcer dyspepsia (64%). Using culture as standard, the urease test showed a sensitivity of 76% and specificity of 100%, while the biopsy stain had a sensitivity of 97%. The presence of acute inflammation in the antrum and body of the stomach closely correlated with the presence of the organism. Somewhat at variance with previous studies, our study indicated that H pylori in the body mucosa was strongly associated with chronic superficial gastritis with and without acute inflammation. Such a finding may reflect the natural history of infection due to H pylori and the advanced age of our patients.