A simple routine endoscopic screening test has been sought for the diagnosis of chronic atrophic gastritis. An endoscopic-bioptic study was therefore carried out on 850 subjects presenting consecutively at a Digestive Endoscopy Department with dyspeptic-pain symptomatology. In a first sample of 389 patients, 2 biopsies of the gastric body and 2 of the gastric antrum were carried out, independently of the endoscopically documented macroscopic picture. Atrophic changes were in this way encountered in 65 patients (16.7%). In a second group of 461 patients, intragastric pH was determined extemporaneously during endoscopy. pH was = or greater than the chosen threshold value (3.5) in 117 patients and less than this value in 344. In all subjects with pH greater than 3.5 and, by comparison, in 130 with pH less than 3.5 biopsy was carried out on the gastric mucosa, 2 biopsies of the body and 2 of the antrum. Using this approach it was possible to determine the presence of atrophic changes in the gastric mucosa in 57 of 117 (48%) and in 25 of 130 (20%) respectively. In total, chronic atrophic gastritis was diagnosed in 83 of 461 subjects (18%). This percentage is comparable to that observed in the frequency of chronic atrophic gastritis using the more demanding and less selective test of bioptic sampling indiscriminately for all patient. So, the straight-forward determination of intragastric pH in a sample of gastric juice taken during digestive endoscopy would appear to meet the criteria demanded for a screening test and its wider use is recommended in routine endoscopic practice.