Pulmonary sequestration is a congenital anomaly in which an aberrant systemic artery arising from the thoracic or upper abdominal aorta supplies part of the lungs, usually the lower lobe. The sequestered lung may be anatomically distinct from the remainder of the lobe (extralobar), or may be included in the substance of the lobe, in which case it may or may not have bronchial communication with the rest of the bronchial tree. The patients present, often in the first two decades of life, with recurrent and severe bronchopulmonary infections. Associated anomalies are present, especially in the extralobar variety. Nine cases of sequestration are reviewed, stressing significant clinical, radiological, and arteriographic findings. Preoperative demonstration of the anomalous vessel by aortography has contributed significantly to the planning and safety of the surgical procedure, which was generally a lower lobectomy. Eight out of nine patients survived the procedure.