A 62-yr-old male with a history of high blood pressure was admitted for persistent dyspnoea and a right-sided pleural effusion, complicated by a recent episode of shock. There was no history of trauma and the patient denied any thoracic pain. A chest tube was inserted which released nonclotting bloody fluid. A thoracic computed tomographic scan of the chest revealed an aneurysm of the inferior third of the descending thoracic aorta. The patient underwent a successful prosthetic graft replacement. We emphasize that rupture of aortic aneurysms should be considered in the evaluation of spontaneous haemothorax even if it is right-sided and not associated with pain.