The prevalence of Campylobacter pylori (CP) rises with age, as does gastritis. There is now convincing evidence that CP is causative in the majority of cases of active chronic gastritis and that its eradication substantially improves the severity of the gastritis, even back to normal in some cases. A small minority of people may have other factors causing their gastritis, bile reflux, or anti-inflammatory drugs, for example, CP causes temporary dyspeptic symptoms when an individual receives an acute infection for the first time, but what is much less certain is whether or not CP is responsible for chronic dyspeptic symptoms, and whether eradication of CP will improve dyspepsia. At present the therapeutic trials are too few and too small to be sure, but some individuals may benefit.