AIM: To validate the Rockall scoring system for predicting outcomes of rebleeding, and the need for a surgical procedure and death.METHODS: We used data extracted from the Registry of Upper Gastrointestinal Bleeding and Endoscopy including information of 1869 patients with non-variceal upper gastrointestinal bleeding treated in Canadian hospitals.Risk scores were calculated and used to classify patients based on outcomes. For each outcome, we used x2 goodness-of-fit tests to assess the degree of calibration,and built receiver operating characteristic curves and calculated the area under the curve (AUC) to evaluate the discriminative ability of the scoring system.RESULTS: For rebleeding, the x2 goodness-of-fit test indicated an acceptable fit for the model [x2 (8) = 12.83,P = 0.12]. For surgical procedures [x2 (8) = 5.3, P = 0.73]and death [x2 (8) = 3.78, P = 0.88], the tests showed solid correspondence between observed proportions and predicted probabilities. The AUC was 0.59 (95% CI:0.55-0.62) for the outcome of rebleeding and 0.60 (95% CI: 0.54-0.67) for surgical procedures, representing a poor discriminative ability of the scoring system. For the outcome of death, the AUC was 0.73 (95% CI: 0.69-0.78),indicating an acceptable discriminative ability.CONCLUSION: The Rockall scoring system provides an acceptable tool to predict death, but performs poorly for endpoints of rebleeding and surgical procedures.