Objective: The objective of this study was to establish the frequency of preconditions for gastric cancer including atrophy, metaplasia, dysplasia and achlorhydria (pH > 5) in first degree relatives of patients with gastric cancer (FDR- GC). Design: This is a prospective case-control study with incidental cases. Patients: One hundred twelve first de - gree relatives of gastric cancer patients (case group) were paired by age and gender to 117 patients with functional dyspepsia but without GC family history (control group). Study location: This study was conducted in the gastroen- terology service of a level three hospital in Bogota, from March 1 st , 2011 to March 31 st , 2012. Procedures conduc- ted: High digestive endoscopy, gastric pH measurements and gastric biopsies were performed. Measurements: We evaluated and compared endoscopic and pathological measurements as well as measurement of gastric pH. Results: The case group's 60 % frequency of pangastritis was higher than the control group's 28.8% (OR 3.32, CI 1.92 to 5.74, p < 0.05). There were findings suggestive of atrophy in 19.6% of the case group patients and in 7.7 % of the control group (OR 2.65, CI 1.16 to 6. 04, p < 0.05), findings suggestive of intestinal metaplasia in 12.5% of the case group and 0% of the control group, alkaline pH in 35.7 % of the case group and 7 % of the control group (OR 5.94, CI 2.72 to 12.98, p < 0.05). There were 4 cases of low grade dysplasia, two cases of high grade dysplasia (P <0.005), and two of early GC (NS). Conclusions: FDR-GCs had more achlorhydria, premalignant conditions, dysplasia and GC than control patients. The measurement of gastric pH is sensitive for detecting gastric atrophy. FDR-GC patients should be routinely screened with endoscopy and gastric pH measurement.