Evidence that the overloaded heart secretes brain natriuretic peptide (BNP)1 suggests that measurement of plasma BNP concentrations in athletes with left ventricular (LV) hypertrophy may assist in the recognition of organic heart disease. Accordingly, we assessed the diagnostic value of BNP measurement before and after incremental treadmill exercise until exhaustion in 3 joggers who were recently diagnosed with apical-type hypertrophic cardiomyopathy (HC) by echocardiography, in 7 competitive long-distance runners, and 6 hypertensive subjects with echocardiographically documented eccentric LV hypertrophy2 (i.e., LV mass index >125 g/m2 and relative wall thickness of <0.45 [2 × posterior wall thickness/LV end-diastolic dimension]). All 6 hypertensive subjects were treated with calcium antagonists and their arterial blood pressure was well controlled. Another 6 sedentary subjects with normal echocardiograms served as controls. All subjects were men and gave informed, signed consent.