Background The prognostic value of shock index ( SI ), heart rate divided by systolic blood pressure, in stroke for clinical outcomes other than mortality is not well understood. Methods and Results We examined the Get With The Guidelines-Stroke ( GWTG -Stroke) data to explore the usefulness of SI in predicting in-hospital outcomes in 425 808 acute stroke cases (mean age: 71.0±14.5 years; 48.8% male; 89.7% ischemic stroke and 10.3% intracerebral hemorrhage) admitted between October 2012 and March 2015. Compared with patients with SI of 0.5 to 0.7, patients with SI >0.7 (13.6% of the sample) had worse outcomes, with adjusted odds ratios of 2.00 (95% confidence interval [ CI ], 1.92-2.08) for in-hospital mortality, 1.46 (95% CI , 1.43-1.49) for longer length of hospital stay >4 days, 1.50 (95% CI , 1.47-1.54) for discharge destination other than home, 1.41 (95% CI , 1.38-1.45) for inability to ambulate independently at discharge, and 1.52 (95% CI , 1.47-1.57) for modified Rankin Scale score of 3 to 6 at discharge. Results were similar when analyses were confined to those with available National Institutes of Health Stroke Scale (NIHSS) or within individual stroke subtypes or when SI was additionally included in the models with or without blood pressure components. Every 0.1 increase in SI >0.5 was associated with significantly worse outcomes in linear spline models. The addition of SI to existing GWTG -Stroke mortality prediction models without NIHSS demonstrated modest improvement, but little to no improvement was noted in models with NIHSS . Conclusions SI calculated at the point of care may be a useful prognostic indicator to identify those with high risk of poor outcomes in acute stroke, especially in hospitals with limited experience with NIHSS assessment.