Non-cardiac chest pain accounts for 2-5% of all emergency presentations. In the United States, it has been estimated approximately that US$8 billion was spent annually for the initial care of patients suspected to have an acute coronary syndrome, but who were subsequently found not to have coronary artery disease (1). The most common cause of non-cardiac chest pain is gastro-oesophageal reflux disease (2). Two randomized, double-blind, placebo-controlled trials on the use of omeprazole versus placebo for the treatment of NCCP have been published in the western population and reported an efficacy of 62% to 80% (3,4). High-dose omeprazole was used in the previous trials (3,4). Recently, it has been shown that rabeprazole, which is a newly developed benzimidazole proton pump inhibitor, is a more potent and rapid inhibitor of H+,K+-ATPase and acid secretion than omeprazole, lansoprazole and pantoprazole (5,6). Whether the above findings applied to Chinese population is unknown. Thus we would like to propose a randomized double-blind placebo-controlled trial to study the effects of high-dose proton pump inhibitor for the treatment of non-cardiac chest pain in Chinese population. The aim of this study is to evaluate the efficacy of high-dose proton pump inhibitor for the treatment of gastro-oesophageal reflux related non-cardiac chest pain.