Bleeding peptic ulcer is a common and life threatening condition. Endoscopic therapy has become the mainstay of controlling bleeding. Recurrent bleeding after endoscopic control occurs in about 20% of patients with a high associated mortality. We previously demonstrated that the adjunct use of high dose proton pump inhibitor reduces risk of recurrent bleeding and thereby improves patients' outcome [Lau JY N Engl J Med 2000]. The newer PPI, esomeprazole, is an S-isomer of omeprazole. Esomeprazole is more effective in gastric acid control as measured by both basal and pentagastrin acid output when compared to omeprazole. Esomeprazole when given orally at a lower dose achieves a similar gastric control than intravenous esomeprazole. The gastric pH with a high dose esomeprazole when given either orally or intravenously has not been measured among Hong Kong Chinese. If a high dose oral esomeprazole achieves a similar pH control near gastric neutrality, the oral regime can be used in place of the intravenous formulation. This represents significant convenience in dosing and cost savings.