OBJECTIVE The authors aimed to design a score for stratifying patients with brain arteriovenous malformation (BAVM) rupture, based on the likelihood of a poor long-term neurological outcome. METHODS The records of consecutive patients with BAVM hemorrhagic events who had been admitted over a period of 11 years were retrospectively reviewed. Independent predictors of a poor long-term outcome (modified Rankin Scale score ≥ 3) beyond 1 year after admission were identified. A risk stratification scale was developed and compared with the intracranial hemorrhage (ICH) score to predict poor outcome and inpatient mortality. RESULTS One hundred thirty-five patients with 139 independent hemorrhagic events related to BAVM rupture were included in this analysis. Multivariate logistic regression followed by stepwise analysis showed that consciousness level according to the Glasgow Coma Scale (OR 6.5, 95% CI 3.1-13.7, p < 10-3), hematoma volume (OR 1.8, 95% CI 1.2-2.8, p = 0.005), and intraventricular hemorrhage (OR 7.5, 95% CI 2.66-21, p < 10-3) were independently associated with a poor outcome. A 12-point scale for ruptured BAVM prognostication was constructed combining these 3 factors. The score obtained using this new scale, the ruptured AVM prognostic (RAP) score, was a stronger predictor of a poor long-term outcome (area under the receiver operating characteristic curve [AUC] 0.87, 95% CI 0.8-0.92, p = 0.009) and inpatient mortality (AUC 0.91, 95% CI 0.85-0.95, p = 0.006) than the ICH score. For a RAP score ≥ 6, sensitivity and specificity for predicting poor outcome were 76.8% (95% CI 63.6-87) and 90.8% (95% CI 81.9-96.2), respectively. CONCLUSIONS The authors propose a new admission score, the RAP score, dedicated to stratifying the risk of poor long-term outcome after BAVM rupture. This easy-to-use scoring system may help to improve communication between health care providers and consistency in clinical research. Only external prospective cohorts and population-based studies will ensure full validation of the RAP scores' capacity to predict outcome after BAVM rupture.