Core Tip: This review provides data on Helicobacter pylori (H. pylori) as one of the recently identified human bacterial pathogens. On the one hand, its role as a human pathogenic bacterium that is commonly found in patients with chronic gastritis, peptic ulcer disease, and gastric cancer is discussed. On the other hand, the high prevalence of H. pylori in the population and its asymptomatic coexistence with humans in most of the world’s population indicates its persistence in the body as a representative of the microbiome and as a nonpathogenic microorganism. The presented data suggest that there is an apparent ambiguity of the problem and a need for an analytically developed, comprehensive approach to study the effect of H. pylori infection on human health and to perform eradication therapy.