OBJECTIVES: To determine the predictive power of B-type natriuretic peptide (BNP) regarding death in older, functionally impaired patients with multiple comorbidity. DESIGN: Prospective cohort study. SETTING: Specialist geriatric assessment clinic and day hospital. PARTICIPANTS: Two hundred ninety-nine older, functionally impaired patients, mean age 79 at enrollment. MEASUREMENTS: Full clinical history and examination, baseline BNP, and echocardiography. Date and cause of death were ascertained from Scottish death records. Kaplan-Meier survival curves were constructed for quartiles of log (BNP), and the contribution of BNP to prediction of death was investigated. RESULTS: The follow-up period ranged from 3.9 to 5.2 years (mean 4.4 years). BNP was a powerful independent predictor of all-cause and cardiovascular mortality. BNP was a more powerful predictor than blood pressure, diabetes mellitus, smoking, echocardiographic left ventricular hypertrophy, left ventricular systolic dysfunction, or age. BNP predicted death in those with and without a previous cardiovascular event at baseline. CONCLUSION: BNP has significant predictive power for death in older, functionally impaired patients.