['To evaluate the association of both Helicobacter pylori (Hp) infection and advancing age with increased prevalence of atrophic gastritis.', 'Two hundred and thirty-eight subjects who had no esophagitis, peptic ulcers, or malignancies in the upper gastrointestinal tract were divided into three groups according to age: group A, < 30 yr; group B, 30-49 yr; group C, > or = 50 yr. Two biopsy specimens were obtained from the lesser curvature of the antrum and two from the anterior and posterior walls of the fundus to assess the degree of gastritis and histological evidence of Hp infection. Hp infection was evaluated by Giemsa staining and serum IgG antibodies. Serum gastrin (SG) and pepsinogen (PG) were determined by radioimmunoassay.', 'In all age groups, the prevalence of atrophic gastritis was significantly more common in subjects with evidence of Hp infection. In Hp-positive subjects, the prevalence of atrophic gastritis increased with advancing age. Atrophic gastritis was extremely rare, regardless of age, in Hp-uninfected patients. SG increased, and PG I and the PG I:II ratio decreased with age in Hp-positive subjects. This trend was not apparent in Hp-negative subjects.'] Is helicobacter pylori infection the major risk factor for atrophic gastritis?