helicobacter pylori (hp) is a bacterium causing colonization and infection of gastric epithelium of man. infection allows appearance of a gastritis that may to evolve to a peptic ulcer, a gastric adenocarcinoma, or a type malt lymphoma. in other cases, infection has a silent presentation. authors studied presence of hp in patients with gastritis and in others with a healthy mucosa, seen in endoscopy consultation of "hermanos ameijeiras" surgical clinical hospital by others disorders in high digestive tract pathways. fifty patients were investigated, 30 of them had an erosive gastritis, and 20 had a healthy mucosa histology confirmed. hc was detected by amplification of a fragment of ure a gen, by means of polymerase chain reaction (pcr), in 90% of cases with erosive gastritis, and in 75 % of subjects with a healthy mucosa. the reason of odds ratio (or) was of 3 with a confidence interval (ic) of 0.52-18.9. we conclude that hp infection is so high in patients with gastritis than in those with a healthy gastric mucosa.