Background. Helicobacter pylori infection causes chronic gastritis and results in increased serum concentrations of pepsinogens I and II as well as gastrin, while the ratio of pepsinogen I to II (I : 11) is decreased. Inducible nitric oxide synthase (iNOS) is induced in H. pylori-associated gastritis and may modulate inflammation. However serum nitrate and nitrite (NOx) concentrations in patients with H. pylori-induced chronic gastritis have not been reported. We examined differences in serum NOx between H. pylori-negative and positive volunteers relative to differences in pepsinogens and gastrin. Materials and methods. Sera from 80 healthy asymptomatic volunteers younger than 36 years were analyzed for anti-H, pylori antibody; NOx, gastrin and pepsinogens. Results. In H. pylori antibody-positive subjects serum NOx concentrations were higher than in negative subjects (p <.005). In H. pylori-negative subjects, NOx correlated with pepsinogen II (r =.405,p <.05). In subjects with low pepsinogen I or II, NOx was higher in H. pylori-positive than negative subjects (p <.001). In subjects with high pepsinogen I : II (6 or higher), serum NOx was higher in H. pylori-positive than in negative subjects. Conclusions. H. pylori-induced gastritis increases serum NOx concentrations more prominently than those of pepsinogen. In H. pylori-negative subjects, serum correlates with serum pepsinogen II.