On the basis of the levels of serum pepsinogen I (S-PGI) and gastrin-17 (S-G-17) as well as Helicobacter pylori antibodies it is possible to establish with high sensitivity and specificity whether the patient has gastritis, whether the gastritis is atrophic or not and in which part of the stomach the atrophic changes are located. The tests enable the identification of patients whose risk of gastric cancer, consequences of vitamin B12 deficiency or peptic ulcer is increased considerably and who should therefore undergo gastroscopy. They also facilitate diagnosis of non-atrophic Helicobacter gastritis enabling treatment before endoscopy.