This study compared the correlation and prognostic utility of B-type natriuretic peptide (BNP) and the N-terminal fragment of proBNP (NT-proBNP) in 171 outpatients with renal dysfunction. The NT-proBNP correlated well with BNP in all cases (r = 0.911; P pound .01), regardless of degree of renal impairment or type of left ventricular dysfunction. BNP and NT-proBNP concentrations (P < .005) and their ratios (P pound .01) increased as the glomerular filtration rate (GFR) declined, indicating a greater effect of GFR on NT-proBNP levels. Both natriuretic peptide levels were higher in patients with systolic dysfunction (P < .05) compared with patients with normal echocardiograms. In contrast, BNP and NT-proBNP levels were below the diagnostic cutoffs for congestive heart failure exacerbations in patients with normal heart function or diastolic dysfunction, with no statistical difference between these groups (P = .99). Both peptides are useful prognostic tools for predicting mortality and cardiac hospitalization in renal patients.