AIMS: This study was designed to evaluate a new NT-proBNP monitoring concept in outpatients with systolic heart failure (HF). METHODS AND RESULTS: This was a multicentre, prospective randomized open-label blinded endpoint study. A total of 407 systolic HF patients were allocated to either clinical management (n = 208) or clinical management + NT-proBNP monitoring (n = 199) and followed for 2.5 years. If NT-proBNP increased >30%, a clinical checklist was completed and treatment initiated. The patients were matched at randomization and were 73 years old, 25% were females, 85% were NYHA class I-II, LVEF was 30%, and NT-proBNP 1955 pg/mL. NT-proBNP monitoring did not improve outcome, the hazard ratio for the primary composite endpoint (death or a cardiovascular admission) being 0.96 [95% confidence interval (CI) 0.71-1.29, P = 0.766]. NT-proBNP monitoring did not induce a significant change in the pharmacological strategy (P > 0.05 for all comparisons). In patients in whom NT-proBNP increased >30% (25% of the patients) during follow-up, a higher frequency of admission (69% vs. 47%, P = 0.002), a higher number of admission days (14 vs. 5 days, P = 0.003) and number of admissions (2 vs. 1, P = 0.009), and a lower quality of life (P = 0.032) and a poorer functional class (37% vs. 18% in NYHA class III-IV, P <0.001) were observed. CONCLUSIONS: Adding serial measurements of NT-proBNP to optimal clinical management was not associated with a change in pharmacological strategy and did not improve outcome. However, survivors in whom NT-proBNP increased >30% showed a poorer functional class, clinical outcome, and quality of life.Trial registrationwww.centerwatch: 173491 (NorthStar).