AIM: To review whether brain natriuretic peptides (BNP) can be used as a surrogate for the traditional methods of assessing functional status in interventional studies of patients with left ventricular systolic dysfunction (LVSD). METHODS AND RESULTS: The traditional methods for assessing functional status including New York Heart Association (NYHA) class, exercise intolerance and quality of life were reviewed in relation to BNP measurements in patients with LVSD. A meta-analysis of four studies evaluating BNP levels versus exercise peak oxygen uptake or 6-minute walking distance showed a significant correlation, but a low R-value of -0.59. Studies using BNP levels for optimisation of heart failure therapy showed conflicting results concerning the correlation between the functional improvement and changes in BNP levels. Conflicting results were also found concerning the utility of BNP levels as a surrogate to predict efficacy of the various anti-congestive therapies on heart failure outcome. CONCLUSION: The results of the studies examining BNP measurement as a surrogate for functional status and drug efficacy in patients with LVSD are conflicting. Further studies are necessary to settle the place of BNP measurement as surrogate marker for exercise tolerance, NYHA classification and in assessing efficacy of different interventions in the clinical trials.