<h4>Background</h4>While the N-terminal pro-brain-type natriuretic peptide (NT-proBNP) at rest is known to be associated with prognosis in pulmonary arterial hypertension (PAH), it is unclear if the NT-proBNP response to exercise (ΔNT-proBNP) can contribute to a better assessment of disease severity.<h4>Methods</h4>We investigated the association of NT-proBNP values at rest and during peak exercise with hemodynamics and cardiopulmonary exercise testing parameters in 63 therapy-naive PAH patients.<h4>Results</h4>The median NT-proBNP increases from 1414 at rest to 1500 pg/ml at peak exercise. Here, NPPB is linked to pulmonary arterial hypertension.