Physicians, patients, and families rely on clinical factors associated with stroke mortality to guide decisions of care and set goals of medical therapy. However, these factors, including age and baseline neurologic impairment, are at best imperfect predictors and additional prognostic tools are needed. Biomarkers such as B-type natriuretic peptide (BNP) have potential. However, for a biomarker to be of clinical utility, it needs to add information beyond what clinical predictors can provide. BNP is produced by myocardial tissue in response to strain and acts to reduce systolic blood pressure through vasodilation and natriuresis. In stroke, BNP has been associated with increased mortality.