Abstract: OBJECTIVE To explore the effects of CYP2C19 gene polymorphism on the efficacy of esmeralazole in the treatment of gastroesophageal reflux disease. METHODS A total of 92 patients with gastroesophageal reflux disease admitted to the department of gastroenterology of The 901st Hospital of the PLA Joint Logistics Support Force from January 2019 to August 2019 were selected. DNA microarray method was applied to perform genetic typing in the patients, and the patients were divided into three groups according to the genotype:32 patients of extensive metabolizer(EM), 36 patients of intermediate metabolizer(IM), and 24 patients of poor metabolizer(PM). Using the 2-week regimen of esomeprazole 40 mg qd, 24-hour gastric pH and curative effects were respectively measured by digestive endoscopy on 7th and 14th day. RESULTS On the 7th day and 14th day after the treatment of esomeprazole, the total time percentages of pH> 4 in EM, IM and PM metabolic patients were significantly different(P<0.05). On the 14th day after the treatment of esomeprazole, there was a significant difference in the clinical efficacy of EM, IM and PM metabolic patients(P<0.05). CONCLUSION The acid inhibition and clinical efficacy of esomeprazole in the treatment of gastroesophageal reflux disease are closely related to CYP2C19 gene polymorphism.