Pulmonary arterial hypertension (PAH) has evolved from an untreatable condition to a disease for which several classes of drugs have now been approved, including various prostanoids, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. Because the pathogenesis of pulmonary hypertension is increasingly understood, various new substances are now under clinical investigation, including serotonin antagonists, vasoactive intestinal peptide, stimulators of soluble guanylate cyclase and tyrosine kinase inhibitors. Several of these compounds hold promise for the future therapy of PAH, especially as regression of pulmonary vascular remodeling appears to become a realistic possibility with the combination of established and novel treatments.