A strong association between persistent infection, chronic inflammation and cancer has been described. Helicobacter pylori is the main cause of gastric cancer, with 900,000 new cases yearly. Helicobacter colonization triggers the gastric epithelial cells to secret IL-8, a chemoattractant of immune cells, which persistently infiltrate the infected tissue. High levels of inflammatory cytokines are found, leading to loss of local homeostasis due to altered cell proliferation and apoptosis. It is not known how this local inflammatory response leads to cancer but the expression of mutagenic O2 and N2 free radicals might directly contribute to the irreversible mucosal genomic damage. Epstein Barr Virus is another pathogen associated with gastric cancer. We review here our current knowledge of inflammatory mechanisms at the site of infection that could be important to the development of cancer and that could be shared by other pathogens. This is of great importance since around 25% of cancers are associated with infection.