Although most studies reporting on the examination of Helicobacter pylori infection have focused on the clearance of the bacteria and the rapid disappearance of the neutrophil infiltrates, the evolution of inflammatory and architectural changes in the antral and corporal mucosa following the eradication of H. pylori has not been addressed systematically. This study examines in detail the histopathologic appearance of the antral and corporal mucosa in a group of patients infected with H. pylori and follows the spectrum of morphologic changes in each of them after the eradication of the infection. At least 11 biopsies ("gastric mapping") were obtained from the antrum and body of each of 15 patients with H. pylori. Complete mapping was then repeated 1, 4, and 10 to 12 mo after the eradication of H. pylori by a course of "triple therapy." Each biopsy was assessed in a semi-quantitative fashion for presence of H. pylori, neutrophils, eosinophils, lymphocytes, lymphoid follicles, and intestinal metaplasia. Other features (integrity of surface epithelium, architecture, fibrosis) were evaluated descriptively. Results were compared with those obtained from a control group of 16 uninfected, healthy adult volunteers. H. pylori infection was eradicated in 11 subjects. The disappearance of neutrophils and the normalization of the surface epithelium closely paralleled that of H. pylori. Persistence of even small numbers of neutrophils was a predictor of relapse. Eosinophils and lymphocytes decreased slowly and did not return to normal levels within 1 yr. Lymphoid follicles decreased very slowly in all patients but were still present in all gastric locations at one year after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)