B-type natriuretic peptide (BNP) and its prohormone NT-proBNP are released in response to myocardial wall stress and are established predictors of outcome in heart failure. This article discusses the prognostic value of BNP in aortic stenosis (AS). In recent studies, BNP and NT-proBNP were consistently related to AS severity and symptom status. High or serially rising BNP predicted the short-term need for valve replacement in asymptomatic severe AS. Preoperative BNP or NT-proBNP reflected postoperative outcome. In low-flow low-gradient AS, high BNP greater than 550 pg/mL predicted poor outcome independently of contractile reserve. BNP and NT-proBNP are easy to assess from plasma and improve risk stratification in the whole spectrum of AS.