AIMS: B-type Natriuretic Peptide (BNP) is activated in patients with severe, symptomatic aortic stenosis (AS), but the prognostic value of BNP in this setting has not been extensively studied. This study aimed to assess the prognostic value of the BNP level in symptomatic and asymptomatic patients with severe AS. METHODS: Seventy consecutive patients referred to our echocardiography laboratory for severe AS with preserved left ventricular function were prospectively enrolled (40 men, median age 74 years [62-82]; aortic valve area 0.7 cm2 [0.6-0.8]; transaortic gradient 48 mmHg [38-60], and left ventricular fractional shortening 38% [32-43]). C-terminal BNP serum level at enrollment was evaluated against baseline functional and echocardiographic parameters as well as clinical outcome. RESULTS: BNP level was elevated in the presence of symptoms and increased with NYHA functional class. BNP serum level >66 pg/ml detected symptomatic patients with a sensitivity, specificity and accuracy of 84%, 82% and 84%, respectively. In symptomatic and asymptomatic patients, BNP level was a strong independent predictor for cardiovascular death by multivariable analysis adjusted to age and NYHA functional class. CONCLUSIONS: BNP serum level allows to differentiate symptomatic from asymptomatic patients with severe AS. BNP is an independent predictor of outcome in these patients and may be helpful for risk stratification.