Primary pulmonary hypertension is a rare disease of unknown etiology, whereas secondary pulmonary hypertension is a complication of many pulmonary, cardiac and extrathoracic conditions. Chronic obstructive pulmonary disease, left ventricular dysfunction and disorders associated with hypoxemia frequently result in pulmonary hypertension. Regardless of the etiology, unrelieved pulmonary hypertension can lead to right-sided heart failure. Signs and symptoms of pulmonary hypertension are often subtle and nonspecific. The diagnosis should be suspected in patients with increasing dyspnea on exertion and a known cause of pulmonary hypertension. Two-dimensional echocardiography with Doppler flow studies is the most useful imaging modality in patients with suspected pulmonary hypertension. If pulmonary hypertension is present, further evaluation may include assessment of oxygenation, pulmonary function testing, high-resolution computed tomography of the chest, ventilation-perfusion lung scanning and cardiac catheterization. Treatment with a continuous intravenous infusion of prostacyclin improves exercise capacity, quality of life, hemodynamics and long-term survival in patients with primary pulmonary hypertension. Management of secondary pulmonary hypertension includes correction of the underlying cause and reversal of hypoxemia. Lung transplantation remains an option for selected patients with pulmonary hypertension that does not respond to medical management.