Objective: The primary aim of this study was to describe in-hospital mortality in subarachnoid hemorrhage patients requiring ICU admission. Secondary aims were to identify clinical characteristics associated with inferior outcomes, to compare subarachnoid hemorrhage mortality with other neurological diagnoses, and to explore the variability in subarachnoid hemorrhage standardized mortality ratios. Design: Multicenter, binational, retrospective cohort study. Setting: Data were extracted from the Australian and New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation Adult Patient Database. Patients: All available records for the period January 2000 to June 2015. Interventions: Nil. Measurements and Main Results: A total of 11,327 subarachnoid hemorrhage patients were identified in the Australian and New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation Adult Patient Database. The overall case fatality rate was 29.2%, which declined from 35.4% in 2000 to 27.2% in 2015 (p = 0.01). Older age, nonoperative admission, mechanical ventilation, higher Acute Physiology and Chronic Health Evaluation III scores, lower Glasgow Coma Scale, and admission prior to 2004 were all associated with lower hospital survival in multivariable analysis (p < 0.05). In comparison with other neurological diagnoses, subarachnoid hemorrhage patients had significantly greater risk-adjusted in-hospital mortality (odds ratio, 1.89 [95% CI, 1.79-2.00]). Utilizing data from the 5 most recent complete years (2010-2014), three sites had higher and four (including the two largest centers) had lower standardized mortality ratios than might be expected due to chance. Conclusions: Subarachnoid hemorrhage patients admitted to ICU in Australia and New Zealand have a high mortality rate. Year of admission beyond 2003 did not impact risk-adjusted in-hospital mortality. Significant variability was noted between institutions. This implies an urgent need to systematically evaluate many aspects of the critical care provided to this patient group.