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Background: Inverse association between hospital case-volume and case-fatality has been observed for various nonsurgical interventions and surgical procedures., Aims: To study the impact of hospital case-volume on outcome after aneurysmal subarachnoid hemorrhage (aSAH)., Methods: We included aSAH patients who underwent aneurysm coiling or clipping from tertiary care medical centers across three continents using the Dr Foster Stroke GOAL database 2007-2014. Hospitals were categorized by annual case-volume (low volume: <41/year; intermediate: 41-70/year; high: >70/year). Primary outcome was 14-day in-hospital case-fatality. We calculated proportions, and used multiple logistic regression to adjust for age, sex, differences in comorbidity or disease severity, aneurysm treatment modality, and hospital., Results: We included 8525 patients (2363 treated in low volume hospitals, 3563 treated in intermediate volume hospitals, and 2599 in high-volume hospitals). Crude 14-day case-fatality for hospitals with low case-volume was 10.4% (95% confidence interval (CI) 9.2-11.7%), for intermediate volume 7.0% (95% CI 6.2-7.9%; adjusted odds ratio (OR) 0.63 (95%CI 0.47-0.85)) and for high volume 5.4% (95% CI 4.6-6.3%; adjusted OR 0.50 (95% CI 0.33-0.74)). In patients with clipped aneurysms, adjusted OR for 14-day case-fatality was 0.46 (95% CI 0.30-0.71) for hospitals with intermediate case-volume and 0.42 (95% CI 0.25-0.72) with high case-volume. In patients with coiled aneurysms, adjusted OR was 0.77 (95% CI 0.55-1.07) for hospitals with intermediate case-volume and 0.56 (95% CI 0.36-0.87) with high case-volume., Conclusions: Even within a subset of large, tertiary care centers, intermediate and high hospital case-volume is associated with lower case-fatality after aSAH regardless of treatment modality, supporting centralization to higher volume centers.