In a series of 150 patients submitted for diagnostic gastroscopy, a prospective study of nine anamnesis variables and four exploratory ones was done. Endoscopic and histopathologic diagnoses, as well as the clinical data, were obtained by blinded observers. Helicobacter pylory (Hp) presence in antral mucosa was determined by culture. A clear relationship between Hp presence and peptic ulcer disease, bulboduodenitis and histologic gastritis was found, as expected, but no clinical variable correlated positively with it. We conclude, therefore, that Hp presence in antral mucosa cannot be predicted clinically, a fact probably related to the unspecificity of symptoms in gastroduodenal disease and not to a lack of pathogenicity of this organism.