Pulmonary sequestration is a rare congenital disorder in which a portion of normal lung tissue lacks normal connections with the tracheo-bronchial tree and the pulmonary arteries. We report on three cases of left lower lobe extrapleural sequestrations that have been studied with ultrasound since 1980. In the two more recent cases demonstration of the feeding vessel originating directly in the abdominal aorta by real-time ultrasound permitted very rapid non-invasive diagnosis of the malformation. We recommend that a search should be made for such an aberrant vessel with real-time ultrasound whenever a pulmonary sequestration is suspected.