Abstract Introduction Our aim was to evaluate the role of B-type natriuretic peptide (BNP) percentage variations at 24 hours and at discharge compared to its value at admission in order to demonstrate its predictive value for outcomes in patients with acute decompensated heart failure (ADHF). Methods This was a multicenter Italian (8 centers) observational study (Italian Research Emergency Department: RED). 287 patients with ADHF were studied through physical exams, lab tests, chest X Ray, electrocardiograms (ECGs) and BNP measurements, performed at admission, at 24 hours, and at discharge. Follow up was performed 180 days after hospital discharge. Logistic regression analysis was used to estimate odds ratios (OR) for the various subgroups created. For all comparisons, a P value < 0.05 was considered statistically significant. Results BNP median (interquartile range (IQR)) value at admission was 822 (412 - 1390) pg\mL; at 24 hours was 593 (270 - 1953) and at discharge was 325 (160 - 725). A BNP reduction of >46% at discharge had an area under curve (AUC) of 0.70 (P < 0.001) for predicting future adverse events. There were 78 events through follow up and in 58 of these patients the BNP level at discharge was >300 pg/mL. A BNP reduction of 25.9% after 24 hours had an AUC at ROC curve of 0.64 for predicting adverse events (P < 0.001). The odds ratio of the patients whose BNP level at discharge was <300 pg/mL and whose percentage decrease at discharge was <46% compared to the group whose BNP level at discharge was <300 pg/mL and whose percentage decrease at discharge was >46% was 4.775 (95% confidence interval (CI) 1.76 - 12.83, P < 0.002). The odds ratio of the patients whose BNP level at discharge was >300 pg/mL and whose percentage decrease at discharge was <46% compared to the group whose BNP level at discharge was <300 pg/mL and whose percentage decrease at discharge was >46% was 9.614 (CI 4.51 - 20.47, P < 0.001). Conclusions A reduction of BNP >46% at hospital discharge compared to the admission levels coupled with a BNP absolute value < 300 pg/mL seems to be a very powerful negative prognostic value for future cardiovascular outcomes in patients hospitalized with ADHF.