Pulmonary artery hypertension secondary to chronic lung diseases is a clinical entity with no specific symptoms that can develop as a result of parenchymal lung disorders (COPD-emphysema, sleep apnea syndrome, diffuse parenchymal lung diseases, etc.) and pulmonary vascular disorders (vasculitis, sarcoidosis, etc.). In the clinical history of these chronic and invalidating diseases, pulmonary vasculature goes through various degenerative and/or proliferative changes, responsible of the pulmonary arterial hypertension appearance. The rise in pulmonary artery pressure can be subtle and the progression from an asymptomatic disease to a more severe syndrome is often common in all forms of secondary pulmonary arterial hypertension. Etiopathology of pulmonary artery hypertension secondary to chronic lung diseases is based on one or more of the following mechanisms: hypoxic vasoconstriction, decreased area of pulmonary vascular bed, volume/pressure overload. In these forms, the above three mechanisms show common mediators, all responsible of disease progression but singularly potential reversible. Therapies for secondary pulmonary artery hypertension consist primarily on the treatment of the underlying disease. Therapy is most effective when initiated prior to the onset of irreversible pulmonary vascular damage. In the last two decades, new medical treatments (prostacyclins, endothelin receptor antagonists, phosphodiesterase inhibitors) for pulmonary arterial hypertension have been available for the sporadic and the secondary to systemic sclerosis forms. The role of these drugs in the other forms of pulmonary arterial hypertension has not been well studied yet. This review will go through the pathogenesis and the several therapeutic approaches for pulmonary artery hypertension secondary to chronic pulmonary diseases or pulmonary vasculature disorders.