Over a 15-month period, 399 patients with dyspepsia were investigated for the presence of Campylobacter pylori infection. Half of the patients (50.6%) had Campylobacter organisms in the antrum of the stomach. C. pylori was found in 96.1% of patients with histological changes of chronic active gastritis in the antrum. Of patients with duodenal and gastric ulcers, 87.8% and 87.5%, respectively, had Campylobacter organisms, as did 39.3% of patients with non-ulcer dyspepsia. C. pylori infection was most commonly found in Chinese and Indians. Although the prevalence of infection appeared to increase with age, there was an equal distribution amongst the sexes.