Background/Aims: Eradication rate of H. pylori by high dose proton pump inhibitor and amoxicilin has been reported as up to 90%. The aim of this study was to test the efficacy of high dose rabeprazole and amoxicillin dual therapy for H. pylori eradication in Korea and evaluate the influence of CYP2C19 genotype on eradication rate. Methods: 19 H. pylori positive patient who presented gastric ulcer or duodenal ulcer, were received rabeprazole(40 mg/day, bid) and amoxicillin (2.0 g/day, bid) for 7 days. CYP2C19 genotype status was determined by a PCR- restriction fragment length polymorphism method. After 4 weeks, H. pylori eradication was evaluated by C¹³-urea breath test. Results: H. pylori eradication was achieved in 7/19 patients(36.8%). Side effect was not reported. No significant differences in eradication rates among the homozygous extensive metabolizer, heterozygous extensive metabolizer, poor metabolizer groups were observed; 50%, 0%, 50%, respectively(P=0.296). After failure of dual therapy, patients were submitted to treatment with triple therapy(proton pump inhibitor, amoxicillin, and clarithromycin) for 14 days and showed higher eradication rate(77.8%). Conclusions: Eradication rate of high dose rabeprazole(40mg/day) and amoxicillin dual therapy was too low to be use for H. pylori eradication CYP2C19 genotype did not influence the eradication rates in this regimen. But, trial with higher dose rabeprazole may be considered for H. pylori eradication. (Korean J Helicobacter Res Prac 2002;2:192-196)