To compare H. pylori infection prevalence and gastric mucosa damage in HIV-infected and non-HIV-infected patients, gastric biopsies were systematically taken in 209 individuals who underwent upper Gl endoscopy (102 HIV-infected and 107 non-HIV-infected). H. pylori was found in 42 (41.1%) HIV-infected patients and in 53 (49.5%) non-HIV patients (P = 0.22, chi2 = 1.47, NS). In HIV-positive patients infected with H. pylori the mean CD4 count was higher than in HIV-positive patients without H. pylori (364 and 228 cells/mm3, respectively; P = 0.0001). H. pylori gastritis was more severe in the HIV-positive group (chi2 = 15.02, P = 0.0001). The frequency of H. pylori in gastric mucosa in HIV-infected and non-HIV patients was similar. HIV-infected patients with H. pylori had a higher mean CD4 count than HIV-infected individuals without H. pylori. Gastric lesions associated with H. pylori were more severe in the HIV-positive population.