Helicobacter pylori infection (further as Hp) keeps playing a key role in pathogenesis of gastric diseases. Helicobacter pylori is world widely considered as a leading cause of gastric cancer and was classified by WHO as a carcinogen of the 1st degree. Rising risk of gastric adenocarcinoma development at Hp infection depends on many factors. Potential mechanism of Hp induced stomach carcinogenesis involves bacterial factors, those of the host’s interaction of bacterial and environmental factors. Combination of virulent bacterial root and genetically permissive host in an appropriate gastric surroundings (existence of chronic inflammation with atrophy, metaplasia or mucous membrane dysplasis are immensely important), and can lead to development of cancer disease. Instead of all these facts, there are very few unambiguous proofs about positive or negative effect of Hp eradication at the gastric cancer incidence.