The prognostic value of brain natriuretic peptide (BNP) measurement in patients with acute heart failure is not well understood. The aim of this study was to investigate the relationship between the BNP level and mortality and readmission for acute heart failure. We studied 569 consecutive patients who were admitted with a diagnosis of acute heart failure. The BNP level was measured after the patient became clinically stable. The relationship between the BNP level and mortality was assessed by Cox regression analysis, and the relationship with readmission, by competing risks regression analysis. During a median follow-up period of 9 (range, 3-18) months, 156 deaths (27.4%) and 140 readmissions (24.6%) occurred. Multivariate analysis demonstrated a positive linear association between the risk of death and the BNP quintile. In contrast, the BNP level did not predict readmission for acute heart failure, mainly because of the effect of death as a competing outcome.