Helicobacter pylori (formerly Campylobacter pylori) is causally related to active antral gastritis and is highly associated with duodenal and gastric ulcers. However, the relationship of H pylori to nonulcer dyspepsia is less clear. We determined the presence of H pylori in unselected patients who were undergoing upper gastrointestinal tract endoscopy, and we found a prevalence of 37% in 110 patients with nonulcer dyspepsia that was similar to previous data. Patients with nonulcer dyspepsia who had H pylori were found to be significantly older than patients with nonulcer dyspepsia who did not have H pylori. In addition, when stratified according to age, we detected an increased prevalence of H pylori in patients with nonulcer dyspepsia with increasing age, similar to that reported for asymptomatic control populations. This finding casts doubt as to the causal role of H pylori for most patients with nonulcer dyspepsia and stresses the importance of considering epidemiologic factors, such as age, when evaluating the role of H pylori in specific disease states.