Helicobacter pylori has been directly linked with active chronic gastritis, peptic ulceration, and gastric adenocarcinoma in humans. Although a substantial portion of the human population is colonized with H. pylori, the patterns of transmission of the organism remain in doubt, and reservoir hosts have not been identified. This study documents the isolation of H. pylori from domestic cats obtained from a commercial vendor. The isolation of H. pylori from these cats was confirmed by morphologic and biochemical evaluations, fatty acid analysis, and 16S rRNA sequence analysis. H. pylori was cultured from 6 cats and organisms compatible in appearance with H. pylori were observed in 15 additional cats by histologic examination. In most animals, H. pylori was present in close proximity to mucosal epithelial cells or in mucus layers of the glandular or surface epithelium. Microscopically, H. pylori-infected cat stomachs contained a mild to severe diffuse lymphoplasmacytic infiltrate with small numbers of neutrophils and eosinophils in the subglandular and gastric mucosae. Lymphoid follicles were also noted, particularly in the antrum, and often displaced glandular mucosal tissue. Thus, the domestic cat may be a potential model for H. pylori disease in humans. Also, the isolation of H. pylori from domestic cats raises the possibility that the organism may be a zoonotic pathogen, with transmission occurring from cats to humans.