Apoptosis plays a major role in gastrointestinal epithelial cell turnover. We have examined induction of apoptosis by Helicobacter pylori in gastric AGS cells and the role of protein kinase C (PKC) which has been shown to modulate programmed cell death. Incubation of AGS cells with H. pylori resulted in an activation of caspases 3 and 9 and induced programmed cell death. The PKC activator 12- O -tetradecanoylphorbol-13-acetate (TPA) caused translocation of PKC gamma, delta and var epsilon, prevented H. pylori -induced caspase activation and programmed cell death. Cocultivation of AGS cells with H. pylori resulted in a translocation of the atypical PKC isoform PKC lambda. We suggest that inhibition of H. pylori induced apoptosis by PKC activation can play a role in the process of neoplastic transformation.