Phosphodiesterase inhibitors like sildenafil have already been shown to improve functional capacity and hemodynamics in the treatment of pulmonary arterial hypertension. Few studies address the effects of new phosphodiesterase inhibitors as tadalafil. We report a case of a patient with idiopathic pulmonary arterial hypertension in functional class IV (New York Heart Association) with significant response to treatment with tadalafil.