AIM: To investigate the relationship between the -765G > C COX-2 polymorphism and the development of different gastric lesions: atrophy or intestinal metaplasia and gastric adenocarcinoma. METHODS: A cross-sectional study was performed involving 320 Portuguese individuals (210 without evidence of neoplastic disease, 73 patients with gastric adenocarcinomas and 37 with atrophy or intestinal metaplasia) using a PCR-RFLP method. RESULTS: -765C allele was overrepresented in the patients with gastric adenocarcinoma (51%) when compared either with the control group (38%) or patients with atrophy or intestinal metaplasia (27%). Callele was found to be very common in our population (0.22), and a multivariate logistic regression analysis revealed nearly 3-fold increased risk for the progression to gastric adenocarcinoma in patients with atrophy or intestinal metaplasia carrying the -765C allele (OR = 2.67, 95% CI = 1.03-6.93; P = 0.04).considered as another susceptibility marker for gastric adenocarcinoma development in patients with atrophy or intestinal metaplasia. AIM: To investigate the relationship between the -765G > C COX-2 polymorphism and the development of different gastric lesions: atrophy or intestinal metaplasia and gastric adenocarcinoma. METHODS: A cross-sectional study was performed involving 320 Portuguese individuals (210 without evidence of Neoplastic disease, 73 patients with gastric adenocarcinomas and 37 with atrophy or intestinal metaplasia) using a PCR-RFLP method. RESULTS: -765C allele was overrepresented in the patients with gastric adenocarcinoma (51%) when comparing either with the control group (38% ) or patients with atrophy or intestinal metaplasia (27%). Callele was found to be very common in our population (0.22), and a multivariate logistic regression analysis revealed nearly 3-fold increased risk for the progression to gastric adenocarcinoma in patients with atrophy Or intestinal metaplasia carrying the -765C allele (OR = 2.67, 95% CI = 1.03-6.93; P = 0.04).considered as another susceptibility marker for gastric ade Nocarcinoma development in patients with atrophy or intestinal metaplasia.