Pulmonary artery sling is an uncommon and potentially lethal vascular anomaly that can produce airway obstruction. Despite the availability of a corrective operation, the mortality rate remains very high (50 per cent of surgically treated children) due to the high incidence of associated obstructive anormaliies of the tracheobronchial tree. The survivors of corrective operation have done well symptomatically. However, when restudied, most have been found to have no pulmonary blood flow to the left lung. Successful treatment requires early recognition of the anomaly, adequate preoperative investigation for associated anormalies (especially those of the tracheobronchial tree), a technically perfect vascular reconstruction, and meticulous postoperative respiratory therapy.