Endoscopic biopsies from 310 patients were studied for the presence of Campylobacter pylori (Cp). In the first group of 150 patients duodenal and antral biopsies were obtained and in the second (160 patients) biopsies were taken from various sites in the stomach including the antrum, incisura, body and fundus. In the duodenum there was a strong association with active inflammation and the presence of gastric metaplasia. Cp were never seen in the normal duodenum. In the stomach Cp presence was associated with gastritis irrespective of severity and site, but was absent in areas showing intestinal metaplasia. Cp were seen in histologically normal biopsies from all areas of the stomach but were significantly more common in normal fundal than normal antral mucosa.