OBJECTIVE To determine the histopathological types of gastritis, presence of H pylori, and of peptic ulceration in patients aged 70 and over, compared with younger adults. METHODS Gastric antral and corpus biopsy specimens from 112 elderly patients were classified and graded histologically according to the Sydney system. Details of recent antibiotic and non-steroidal anti-inflammatory drug use were recorded. Eighty four of the patients were positive for H pylori IgG antibodies and parietal cell antibodies. The results were compared with those from a series of 124 adult patients aged under 60. RESULTS H pylori were visible at histological examination in only 57 of 87 (65.5%) elderly patients with chronic gastritis (excluding "special forms") compared with 72 of 79 (91.1%) of the younger patients with gastritis (p < 0.0002). Severe atrophy of the corpus mucosa was significantly associated with absence of H pylori (p < 0.002), and was present in eight of 30 elderly patients with helicobacter negative gastritis. Other explanations for absence of H pylori include recent antibiotic intake, more intestinal metaplasia, and lower bacterial load in elderly patients (p < 0.05). Autoimmune gastritis and NSAID use did not seem to be relevant. Serodiagnosis showed reduced sensitivity (81%) in patients who were helicobacter positive histologically, but was positive in 14 of 23 (61%) with H pylori negative gastritis histologically, suggesting either current infection that had been missed or previous infection. Peptic ulceration was significantly associated with NSAID use, but not with H pylori in the elderly. CONCLUSIONS The spectrum of gastritis is different in the elderly, compared with younger adults, due to a significant group with chronic gastritis who are H pylori negative on histological examination. NSAID use, but not demonstration of H pylori (at histological examination) is associated with peptic ulceration in the elderly.