The discovery of Helicobacter pylori (H. pylori) represents one of the most notable events in the field of experimental and clinical medicine with great impact to daily practice even to surgery. It has led to a paradigm shift in the treatment of peptic ulcer disease. For the time period of almost one century, several scientists had described spiral-shaped bacteria in the stomach of animals and humans. However, it lasted till the early 1980s when Robin Warren and Barry Marshall successfully cultured H. pylori and recognised its causal relationship to chronic gastritis and peptic ulcer disease. Since then, our knowledge about H. pylori and related diseases has been continuously growing. Today, the bacterium is known to be mainly responsible for the development of chronic gastritis, peptic ulcer disease, MALT lymphoma and is considered as the main risk factor for the development of gastric cancer - all this led to a switch in the basic aetiopathogenetic considerations. In particular, eradication of H. pylori helped to i) develop an aetiology-based therapeutic and preventive approach to the diseases listed above according and adapted to findings, stage and manifestation, and ii) define a new role of surgery in the treatment concept. In addition, more and more evidence is being gathered for a possible association between the bacterium and several extragastric diseases.