Persistent infection with Helicobacter pylori confers an increased risk of peptic ulceration and gastric adenocarcinoma. Reactive oxygen and nitrogen species play a crucial role in the progression from normal gastric mucosa to cancer. The aim of the present study was to investigate the plasma malondialdehyde and nitric oxide levels in H. pylori related gastroduodenal diseases and associate their levels with gastric pathology and genotypes of H. pylori. Malondialdehyde and nitric oxide levels in plasma samples of 250 subjects were spectrophotometrically determined. Subsequently, genotypic and histopathological assessment was performed in gastric biopsies obtained during endoscopy. The levels of MDA and NO exceeded in subjects infected with genotype-1 of Hp than those with other genotypes suggesting more precise interaction of highly virulent strains of Hp in eliciting severe tissue damage. In conclusion, the study demonstrates close relationship between the plasma malondialdehyde and nitric oxide levels, gastric histopathology and genotypes of H. pylori.