Etiology of gastric cancer is related to environmental and host factors, Helicobacter pylori infection is the main environmental factor, but it has been also proposed that some major histocomnpatibility complex genes are related to susceptibility and resistance to develop Helicobacter pylori associated gastric diseases. The aim of this study was to study distribution and frequency of some HLA -DQ genes, among Mexican patients harboring gastric diseases. We studied 20 subjects suffering from gastric cancer and 40 subjects harboring Helicobacter pylori-associated chronic gastritis. Diagnosis was confirmed by biopsy. HLA genotyping was performed by a polymerase chain reaction procedure. Ninety nine healthy individuals were also utilized for comparative purposes. Patients with gastric cancer displayed high frequency of HLA-DQA1*0601 (p = 0.003; OR = 20.9, 95% CI = 2.11-506.2) and HLA-DQB1*0501 alleles, the latter when compared to patients with chronic gastritis (p = 0.04; OR = 3.58, 95% CI = 1.05-12.5) and to healthy individuals (p = 0.002; OR = 4.5, 95% CI =1.59-12.7). According to our results, in addition to Helicobacter pylori infection, there are immunogeneic markers of the HLA-DQ region, which are determinant in confering susceptibility for gastric cancer.