The aim of this study was to evaluate the association of NOS2 polymorphisms Ser608Leu (rs2297518) in exon 16, -954G/C and -1173C/T, both in the promoter region, with gastric cancer and chronic gastritis and the association of cancer with risk factors such as smoking, alcohol intake and H. pylori infection. The gene discussed is NOS2; the disease is chronic gastritis.