Twenty years ago Helicobacter pylori was identified in the gastric content and this finding stimulated a multitude of studies and publications that changed drastically our knowledge of common gastric conditions such as peptic ulcer and gastric cancer. This progress has affected significantly our practice and has resulted in great benefits for our patients. The relationship of the bacteria to the pathogenesis of gastritis, peptic ulcer, gastric cancer and gastric lymphoma was firmly established. A large number of individuals are infected (an estimated half of the world's population) while only a minority suffers of the above mentioned conditions, so it became clear that certain strains of the bacteria, susceptibility of the host and environmental factors interplay in causing the damage. The diagnosis of the infection became a standard practice and therapy and prevention of these common conditions has been drastically modified. Eradication of the bacteria resulted in the cure of ulcers, in a dramatic decrease in the rate of its complications and in the ocurrence of gastric cancer. Better sanitary conditions are part of the solution. Also it is successful in the management of certain gastric lymphomas. The treatment however, is expensive and not free of side effects. Further research work is needed to facilitate the diagnosis and less expensive treatments should be available to eradicate Helicobacter pylori throughout the world