Since 1982, when Marshall and Warren highlighted the presence of H. pylori at the apical pole of the epithelial gastric cells, the medical literature has registered a cascade of subsequent researches concerning this amazing bacterium, its action on the human body and the body response. The apogee of these studies and conclusions about the pathogenic role of HP was touched with its certain recognition as class one carcinogenic agent (Peura 1997, WHO), becoming the first bacteria with such an action. The data gathered in the last period identify different virulence factors of HP, but fail to fully explain the relatively low incidence of gastric cancer in HP carriers; therefore, it is now considered that the carcinogenic potential related to HP infection in humans is due to the synergic and complementary association of the bacterial genetic equipment with diet and host response.