Pulmonary hypertension (PH) is a common complication of chronic pulmonary diseases, especially in advanced disease, and is associated with greater mortality and worse clinical course. Patients with symptoms that exceed those expected by their pulmonary disease should be further evaluated by echocardiography. Confirmatory right heart catheterization is indicated in those conditions where the results of the hemodynamic assessment will determine treatment options. The treatment of choice for patients who are hypoxemic and have pulmonary hypertension associated with chronic lung disease is long-term oxygen therapy. Conventional vasodilators or drugs approved for pulmonary arterial hypertension are not recommended in patients with mild-to-moderate PH because they may impair gas exchange and because there is a lack of evidence supporting their efficacy. Patients with severe PH should be considered for referral to a center with expertise in PH and lung diseases. Ideally, these patients should be included in randomized controlled trials to determine which patients are more likely to derive benefit and which therapies are most likely to be successful.