Patients with chronic renal failure who were undergoing dialysis were recently shown to have a low prevalence of duodenal Helicobacter (Campylobacter) pylori colonisation in spite of a high incidence of gastric metaplasia. The prevalence of the organism in the gastric antrum of 50 similar patients was estimated and compared with that in a control group comprising 120 consecutive patients with no renal failure who were being investigated for a variety of symptoms and signs related to the upper alimentary tract. Seventeen of the patients with renal disease had upper gastrointestinal symptoms. The prevalence of antral H pylori was significantly less in patients with renal disease (12, 24%) than in the control group (51, 42%), but was associated with a similar active chronic inflammatory reaction with prominent lymphoid follicles. The prevalence of the bacteria in patients with renal disease was similar to that reported in normal volunteers, and was the same whether the patients had upper gastrointestinal symptoms or not. This low prevalence may be related to the wide variety of medication, including antibiotics, which these patients are prescribed during the course of their illness.