Unilateral pulmonary artery agenesis is a rare congenital anomaly often associated with other cardiovascular abnormalities. It is usually diagnosed and surgically treated in childhood. Subjects without associated cardiac anomalies (isolated unilateral pulmonary artery agenesis) may be asymptomatic or have recurrent respiratory infections. We report a case of left pulmonary artery agenesis in a 35-year-old man complicated by hemoptysis and treated by pneumonectomy. Physicians should be aware of unilateral pulmonary artery agenesis presenting later in life as a source of chronic respiratory symptomatology or hemoptysis.