The investigators will include those patients with adherent clot on gastric or duodenal ulcers after endoscopic confirmation After receiving well explanation and giving written consent, they are enrolled and will be allocated to 2 groups randomly. Those in the first group will receive intravenous omeprazole 40 mg stat and then 40 mg q12h. Those in the second group will receive intravenous omeprazole 80 mg stat and then 8mg/hr infusion. The patients in both groups will receive intravenous omeprazole for 3 days and then oral esomeprazole qd for further treatment of peptic ulcer.

The investigators define rebleeding during admission and within 30 days as primary end points and define surgical intervention for ulcer bleeding, transfusion amount and hospitalization days after allocation as secondary end points.

The investigators will include those patients with adherent clot on gastric or duodenal ulcers after endoscopic confirmation and exclusion of other possible bleeder. Adherent clot is defined that still stays on the ulcer after 200 ml normal saline irrigation (4 times of irrigation with 50 ml syringe). After receiving well explanation and giving written consent, they are enrolled and will be allocated to 2 groups randomly. Those in the first group will receive intravenous omeprazole 40 mg stat and then 40 mg q12h. Those in the second group will receive intravenous omeprazole 80 mg stat and then 8mg/hr infusion. The patients in both groups will receive intravenous omeprazole for 3 days and then oral esomeprazole qd for further treatment of peptic ulcer. The investigators will record the basic data of these patients including age, sex, use of NSAID or anit-coagulant, concomitant major diseases; clinical data including Hb, Plt, PT, the lowest systolic pressure before allocation and heart rate at the same time, shock status, transfusion amount before allocation; endoscopic findings including the location & size of ulcer, size of clot, existence of fresh blood in stomach or duodenum. The investigators will monitor the events of rebleeding during admission and within 30 days, surgery for ulcer bleeding and mortality within 30 days and record the amount of transfusion and hospitalization days after allocation. When rebleeding is suspected , those patient will receive endoscopic examination and appropriate therapy. Further treatment with surgical or angiographic intervention is decided by the attending physicians.These patients will be monitored during admission (2 weeks in average)and then followed up in GI outpatient clinics.

The investigators define rebleeding during admission and within 30 days as primary end points. Rebleeding is defined as the one of the clinical manifestations occurring 6 hours after allocation: 1.hematemesis or bloody stool 2. tarry stool and hemodynamic change (systolic pressure less than 90 mmHg, or heart more than 110 beats per minute ) 3. decrease of Hb more than 2g/dl within 24 hours after elevation of Hb to 10 g/dl with transfusion. The investigators define surgical intervention for ulcer bleeding, transfusion amount and hospitalization days after allocation as secondary end points.

Inclusion Criteria:

• We will include those patients with adherent clot, more than 5 mm, on gastric or duodenal ulcers after endoscopic confirmation and exclusion of other possible bleeder. Adherent clot is defined that still stays on the ulcer after 200 ml normal saline irrigation (4 times of irrigation with 50 ml syringe).

Exclusion Criteria:

• ulcer with active bleeding, suspected malignant ulcer, patients with age less than 18 years old, or allergy to omeprazole