We investigated the question as to how frequently Helicobacter pylori gastritis is present in cases of endoscopically detected giant folds of the corpus and fundic mucosa, and whether this gastritis differs from Helicobacter pylori associated gastritis with no giant folds. Biopsy material obtained from 138 patients with giant folds (sex ratio: 1.0 men: 105 women; average age 61.0 years) was evaluated histologically and compared with that obtained from 1,196 patients with H. pylori associated gastritis without giant folds (1.1 men: 1.0 women; average age 51.9 years). Among the patients with giant folds, H. pylori colonisation of the gastric mucosa was found in 88.4% of the cases. The degree of H. pylori colonisation determines the degree and activity of the gastritis in the antrum and corpus (p < 0.001). A comparison of the degree of colonisation with H. pylori, the degree of gastritis and the activity of the gastritis in patients with giant folds and in H. pylori gastritis without giant folds revealed no statistically significant differences within the antrum. In contrast, in the case of the corpus, a comparison between the two groups showed that H. pylori colonisation, degree of gastritis, and activity of gastritis were statistically significantly more pronounced in patients with giant folds than in patients with H. pylori gastritis but no giant folds (p < 0.0001). A comparative analysis showed that giant fold formation in the fundus and corpus of the stomach may be a consequence of severe high-grade active H. pylori gastritis, that is, a special and rare form of reaction to the colonisation of the gastric mucosa with Helicobacter pylori.(ABSTRACT TRUNCATED AT 250 WORDS)