Pulmonary hypertension affects right ventricular function by imposing an afterload on the right ventricle and, therefore, as pulmonary hypertension worsens, it ultimately reduces cardiac output. It is clear that in interstitial lung disease, progression of the underlying process with the loss of lung parenchyma contributes substantially to outcome. However, the additional burden of pulmonary hypertension often results in rapid deterioration. Pulmonary hypertension may be treatable and thus may enable the patient to survive until other therapy is effective. Until recently, part of the hesitancy in treating pulmonary hypertension in patients with secondary pulmonary hypertension, has been the limited availability of oral or intravenous drugs that affect the pulmonary circuit without causing excessive systemic vasodilatation. The current drugs available for the treatment of pulmonary hypertension, including prostacyclin and endothelin receptor blockers, have been limited by their high costs and, in the case of prostacyclin, the drug delivery systems. Nitric oxide, which has been used both acutely and chronically for pulmonary hypertension in a variety of diseases, also has limited availability. The role of sildenafil and inhaled prostacyclin remains to be evaluated. The use of these agents in the setting of interstitial lung disease needs to be studied, including combination therapy and early initiation of therapy. Their effect on tissue damage, fibrosis, and inflammation needs to be assessed as well as their effect on the arteriopathy and their potential to cause ventilation-perfusion (V/Q) mismatching. There now appears to be evidence to support treating pulmonary hypertension in patients with interstitial lung disease, with a potential for clinical benefit and a molecular basis for doing it.