Unilateral Absence of Pulmonary Artery (UAPA) is a rare congenital malformation that is usually associated with cardiac anomalies. When there is no congenital cardiac abnormality it is rarer still and is termed isolated unilateral absence of pulmonary artery (IUAPA) (4). IUAPA may remain undetected until adulthood and frequently found incidentally on imaging for other indications. Symptoms are usually secondary to complications which include pulmonary hypertension, recurrent respiratory tract infections, bronchiectasis and haemoptysis. We report two cases with widely contrasting presentation and trajectories, leading to individualized management strategies.