[en] Full text: The interest in Helicobacter pylori has not declined in these years. H. pylori causes a chronic gastric infection which is usually life-long and many epidemiological studies have shown that this is probably one of the most common bacterial infections throughout the world involving 30% of the population in developed countries and up to 70-90% of the population in developing regions. Thus, it is clear that the diagnosis of H. pylori infection represents at least a key step in the management of many of the patients referred to the gastroentelogist. Additionally, due to the wide range and relevance of pathologies possibly related to infection, including malignancies, there is the potential for H. pylori to be a major health problem. Improved methods for the diagnosis and follow up treatment of the infection have been developed in the last decades. The use of stable isotopes in non-invasive diagnostic methods, as the breath tests, was the key to a new era of research about H. pylori epidemiology, diagnostic, criteria for the eradication treatment, etc. This paper focuses on the different diagnostic methods employed, especially in those where isotopic techniques are applied. (author)