The indications for aortography in patients sustaining blunt chest trauma increased as the number of radiographic and clinical findings associated with traumatic rupture of the thoracic aorta (TRA) proliferate. No studies demonstrated whether these findings are useful in selecting patients for aortography. In order to determine the predictive value of reported associations in TRA, the presence or absence of 9 radiographic and 9 clinical findings associated with TRA was tabulated and tested for correlation with the results of aortography in 173 consecutive patients who underwent arch aortography from 1975-1980 to rule out TRA following blunt trauma. Mediastinal widening was the most reliable indicator of TRA. All patients less than 65 yr old with TRA presented with mediastinal widening. In patients under 65, the reliability of mediastinal widening to predict TRA was not enhanced by any other clinical or radiographic finding studied. Only 2 of 6 TRA in patients over 65 had mediastinal widening. Only in this group over 65 did other publicized indications for aortography, including pulmonary contusions or multiple rib fractures including ribs 1 and 2, have any association singly or in combination with TRA. All trauma victims who have a widened mediastinum should undergo aortography. Other reported associations by themselves are not absolute indications for aortography except in patients 65 yr old or older.