Background: The Glasgow-Blatchford Bleeding Score (GBS) and Rockall Score (RS) are clinical decision rules that risk stratify emergency department (ED) patients with upper gastrointestinal bleeding (UGIB). We evaluated GBS and RS to determine the extent to which either score identifies patients with UGIB who could be safely discharged from the ED. Methods: We reviewed and extracted data from the electronic medical records of consecutive adult patients who presented with signs or symptoms of UGIB (hematemesis and/or melena) to an academic ED from April 1, 2004, to April 1, 2009. The primary outcome was need for intervention (blood transfusion and/or endoscopic/surgical intervention) or death within 30 days. Results: We identified 171 patients with the following characteristics: mean age of 69.9 years (SD, 17.0 years ), 52% women, 20% with a history of liver disease, and 22% with history of gastrointestinal bleeding. Ninety (52.6%, 95% confidence interval, 44.9-60.3) patients had the primary outcome. GBS outperformed pre-endoscopy RS [area under the receiver operating characteristic curve (AUC) = 0.79 vs 0.62; P = .0001; absolute difference, 0.17]. The prognostic accuracy of GBS and post-endoscopy RS was similarly high (AUC, 0.79 vs 0.72; P = .26; absolute difference, 0.07). The specificity of GBS and RS was suboptimal at all potential decision thresholds. Conclusions: Although GBS outperformed pre-endoscopy RS, the prognostic accuracy of GBS and post-endoscopy RS was similarly high. The specificity of GBS and RS was insufficient to recommend use of either score in clinical practice. © 2012 Elsevier Inc. All rights reserved.