Study design This is a single institution prospective randomized double-blind study. All patient with PUB (Forrest classification I, IIa and IIb: spurting or oozing bleeding, visible vessels and clot) had endoscopic treatments (adrenaline injection and/or heater probe). After successful endoscopic hemostasis, patients are randomized to receive a high or regular dose of omeprazole infusion. After 72 hours, both groups of patients are given oral omeprazole 40mg daily for 4 weeks. All patients are evaluated at the clinic at the end of 4 weeks. The primary end-point is rebleeding. Other secondary endpoints measured are surgery, duration of hospital stay and death.