Chylothorax is an uncommon condition, usually associated with advanced malignant disease or trauma to the thoracic duct. Idiopathic chylothorax and other diverse causes have been anecdotally reported. We describe a rare case of chylothorax, developing as a result of damage to the thoracic duct by a thoracic aortic aneurysm. Tetracycline pleurodesis was successful in controlling the chylous effusion.