Although Helicobacter pylori have been identified in the liver, the role of Helicobacter sp. in human liver diseases remains unclear. This study explored whether H. pylori were internalized and could persist in hepatocytes. The majority of an inoculum of H. pylori (1 x 10(7) colony forming units) adhered to hepatocytes. Using the gentamicin invasion assay we found that approximately 2% were internalized and persisted following passage for more than 2 months. Electron microscopy confirmed the presence of intracellular Helicobacter. The number of adherent or internalized H. pylori was significantly greater with hepatocytes than with gastric epithelial cells (P < 0.05) and was also dependent on cag pathogenicity island (PAI), VacA, OipA, or BabA status. Transmission electron microscopy was used to confirm adherence and invasion of H. pylori into hepatocytes. Internalization of H. pylori was inhibited by antibodies to beta1-integrin receptors, genistein, and cytochalasin D (P < 0.05) consistent with beta1-integrin acting as a surface receptor with additional requirements for tyrosine kinase phosphorylation and actin polymerization. In summary, H. pylori both adhered to and invaded into hepatocytes in vitro, depending on the virulent factors, and persisted within hepatocytes during subcultures. beta1-integrin is likely a receptor involved in internalization of H. pylori into hepatocytes.