Two hundred consecutive patients suffering from non-ulcer dyspepsia were studied for the presence of Helicobacter pylori in antral gastritis and normal antral mucosa, using the combination of culture, modified Giemsa stain and a sensitive immunoperoxidase stain as means of detection. H. pylori gastritis was present in 56% of the cases. The bacterium was present in 75% of cases of normal antral mucosa, however, in low numbers. It is concluded that 87% of patients with non-ulcer dyspepsia are H. polory-positive implying a larger role for the micro-organism as initially thought.