In France, pulmonary arterial hypertension associated with various diseases (connective-tissue diseases, congenital heart diseases, portal hypertension, HIV infection, consumption of anorectic agents) account for approximately 50% of cases of pulmonary arterial hypertension. As it is shown in idiopathic or familial pulmonary arterial hypertension, these forms of pulmonary arterial hypertension are characterized by pulmonary endothelial dysfunction and intense smooth muscle cell proliferation. Their clinical presentation and therapeutic management are similar to those of idiopathic and familial pulmonary arterial hypertension. However, their prognosis differs greatly: it is poor in scleroderma, and much better in congenital heart diseases.