In the present study we assessed the diagnostic accuracy of four commercial IgG enzyme-linked immunosorbent assay (ELISA) kits (Autoplate, H.pylori-EIA-Well, Enzygnost, Helori-test) and evaluated the performance of these tests in patients with fundic atrophic gastritis. Serum antibodies to Helicobacter pylori were measured in 70 out-patients attending endoscopy for dyspepsia and 43 patients with non-autoimmune fundic atrophic gastritis. Using the cut-off values recommended by the manufacturers, and comparing serological findings with gastric biopsy results of dyspeptic out-patients attending endoscopy, the four kits showed a sensitivity and specificity, respectively, of 91% and 96%, for Autoplate, 67% and 100% for H.pylori-EIA-Well, 79% and 100% for Enzygnost, and 81% and 96% for Helori-test. Evaluation in patients with atrophic gastritis revealed a high prevalence of antibodies to Helicobacter pylori (84%) and it demonstrated that patients with and those without gastric colonization by this microorganism had a similar rate of seropositivity (76-84% vs 50-78%). In conclusion, our data demonstrate that: a) this assay is a reliable and valid method to detect gastric colonization by Helicobacter pylori; b) positive serum antibody associated with a negative detection of Helicobacter pylori in the gastric mucosa suggests mucosal atrophy; c) patients with fundic atrophic gastritis should be excluded from studies investigating the value of serology in diagnosing Helicobacter pylori infection.