Rebleeding after initial endoscopic hemostasis in patients with peptic ulcer hemorrhage has been reported in 20~30%. Identification of patients who are at high risk for rebleeding would be expected to improve the outcome of endoscopic hemostasis. The purpose of this study was to evaluate risk factors for rebleeding after initial hemostasis in view of laboratory, clinical and endoscopic characteristics. 189 patients who presented with peptic ulcer bleeding and were treated with endoscopic hemostasis from January 1999 to December 2002 were studied. In peptic ulcer hemorrhage patients, the clinical variables, laboratory findings, endoscopic characteristics of ulcer, endoscopic therapeutic modalities were compared between the patients who bled early (n=29) and who didn't bleed (n=160). The rebleeding rate after initial hemostasis was 15.3% (29/189). Shock, initial hemoglobin level, PRC transfusion amount, FFP transfusion amount, ulcer size and ulcer number are significant risk factors for rebleeding. If the transfusion amount of PRC or FFP increases 1 units, the risk of rebleeding increases 1.13 or 1.23 times, respectively, and if ulcer size increases 1 cm, the risk of rebleeding increases 1.03 times. Early identification of risk factors such the transfusion amount of PRC or FFP and ulcer size may help to predict and improve the prognosis of peptic ulcer hemorrhage.