Pulmonary hypertension (PH) in patients with interstitial lung diseases (ILDs) is not well recognized and can occur in the absence of advanced pulmonary dysfunction or hypoxemia. To address this topic, we identified relevant studies in the English language by searching the MEDLINE database (1966 to November 2006) and by individually reviewing the references of identified articles. Connective tissue disease-related ILD, sarcoidosis, idiopathic pulmonary fibrosis, and pulmonary Langerhans cell histiocytosis are the ILDs most commonly associated with PH. Pulmonary hypertension is an underrecognized complication in patients with ILDs and can adversely affect symptoms, functional capacity, and survival. Pulmonary hypertension can arise in patients with ILDs through various mechanisms, Including pulmonary vasoconstriction and vascular remodeling, vascular destruction associated with progressive parenchymal fibrosis, vascular inflammation, perivascular fibrosis, and thrombotic angiopathy. Diagnosis of PH in these patients requires a high index of suspicion because the clinical presentation tends to be nonspecific, particularly in the presence of an underlying parenchymal lung disease. Doppler echocardiography is an essential tool in the evaluation of suspected PH and allows ready recognition of cardiac causes. Right heart catheterization is needed to confirm the presence of PH, assess its severity, and guide therapy. Management of PH in patients with ILDs is guided by identification of the underlying mechanism and the clinical context. An increasing number of available pharmacologic agents in the treatment of PH allow possible treatment of PH in some patients with ILDs. Whether specific treatment of PH in these patients favorably alters functional capacity or outcome needs to be determined.