Proton pump inhibitors (PPIs) reduce the rate of rebleeding in patients with nonvariceal upper GI bleed (NVGIB). Oral (PO) and intravenous (IV) pantoprazole are equipotent in raising gastric pH. We conducted a pilot study comparing the efficacy of PO vs. IV pantoprazole for reducing rebleeding after NVGIB. Patients with NVGIB were randomized to receive PO (80 mg BID for 3 days) or IV (80-mg IV bolus and 8 mg/hr infusion for 3 days) pantoprazole followed by pantoprazole, 40 mg PO BID, for 30 days. All patients underwent endoscopy within 24 hr and endotherapy was applied where necessary. Twelve patients randomized to the PO and 13 to the IV pantoprazole group were comparable in age, hematocrit, Rockall scores, ulcer characteristics, and endoscopic interventions. Two patients in the IV arm rebled and another in the IV arm developed reversible renal failure. No patient in the PO arm rebled, had organ failure, or had to be changed to IV pantoprazole. We conclude that in this pilot study, the effect of PO pantoprazole on 30-day rebleeding rate in patients with NVGIB was similar to that of IV pantoprazole.