Background: Gastritis represents a state of inflammation, irritation and erosion of gastric mucosa that occur suddenly (acute) or step by step (chronic). H. pylori is a spiral gram-negative rod bacteria that has the ability to colonize and infect the stomach. The cytokine gene interleukin (IL)-1β has been concerned in influencing the pathology of inflammation induced by H. pylori infection. The aim of current study was to study the role of H. pylori infection and IL-1β in pathogenesis of gastritis as well as to study the impact of C-511T (rs16944) polymorphism in the promoter region of the IL-1β gene. Method: This case control study included 90 subjects (60 patients and 30 controls). The detection of H. pylori in serum was achieved by H. pylori Antibody Rapid test cassette. Parameters that weremeasured by ELISA technique were human Interleukin IL-1β level, serum Malondialdehyde concentration and serum Glutathione concentration; whereas serum Total Antioxidant capacity (TAC) was measured by spectrophotometer. IL-IL1β Gene C-511T (rs16944) polymorphism was measured by using Single-Strand Conformation Polymorphism (PCR-SSCP) after amplified by a polymerase chain reaction (PCR) with specific published primers. Results: IL-1β decreased significantly in patients who are positive for H. pylori. However, no significant increment was observed in those negative for H. pylori. Serum MDA increased significantly in gastritis patients when compared with controls. AAlso, there was significant increase in negative H. pylori. Serum GSH and serum TAO increased significantly in negative H. pylori patients when compared with control groups. TAO increased significantly in positive H. pylori when compared with negative H. pylori patients. Haplotypes pattern that increased significantly in gastritis patients were A and B (1.66% and 3, 33%, respectively). Conclusion: In Iraqi population, the gene polymorphisms with D haplotype were associated with chronic gastritis and mainly development of H. pylori--infected individuals. No correlation was found between IL-1β-511 gene polymorphisms in any gastric disease with A, B and C haplotypes. Gastritis with H. pylori infection plays an important role in development of oxidative stress.