The last two decades have seen a steady fall in the morbidity and mortality of thoracic surgical procedures. As a result, where other diagnostic procedures have failed, it has become accepted practice to perform exploratory thoracotomy for accurate diagnosis of mediastinal masses. In April 1953, one of us (L. H. R.) performed an exploratory thoracotomy on a patient with a rounded mass in the right cardiophrenic angle. The mass was found to be a greatly elongated descending thoracic aorta which had crossed in front of the spine into the right hemithorax, turned sharply on itself, and re-entered the left hemithorax. This case alerted us to the possibility of this condition and resulted in the collection of 2 additional cases. The importance of preoperative diagnosis and the paucity of references in the literature to a buckled descending thoracic aorta presenting as a mass in the right hemithorax have prompted the reporting of these 3 cases. Case I: A 51-year-old white female, a patient in the Manteno State ...