Although stress ulcer is a complication that can cause significant mortality and morbidity in critical patients with risk factors, there is still lack of consensus about its prophylaxis. There are also few data available from Taiwan. H2 blockers are commonly used due to convenience. Some prefer sucralfate (a mucosal protective agent) for the sake of less association with nosocomial pneumonia. Recently, proton pump inhibitors were shown to have good prophylactic effects for stress ulcer. Pantoprazole (iv) is the first intravenous form of proton pump inhibitor that was approved by FDA. There are some reports about its application for treatment of peptic ulcer bleeding. It also has good acid suppression effect in patients under critical care. We expect that intravenous pantoprazole will have a role in stress ulcer prophylaxis.