Pulmonary sequestration is an unusual congenital malformation characterized by the presence of nonfunctioning lung tissue which usually has no communication with the normal bronchial tree and receives its blood supply from an anomalous systemic artery. We present a case of extralobar pulmonary sequestration experienced recently. The patient was 13 month old female with a complaint of fever, coughing and tachypnea. Chest film showed large homogeneous opacity in left lower lung field. At operation, a homogeneous mass was located between the left upper lobe and lower lobe, measuring 4X6X5cm in dimension. The aberrant artery was originated from the descending thoracic aorta, 1 cm in length and 3 mm in diameter. After division and ligation of the aberrant artery, sequestrectomy and lingular segmentectomy was done due to abscess formation. The postoperative course was smooth. She was discharged on postoperative thirteenth day.