BACKGROUND: Motor vehicle collision-related blunt thoracic aorta injury (BAI) is rare and highly lethal. Vascular disease as related to advancing age potentially subjects older adults to increased risk of BAI; the mechanisms associated with such injuries may be different as compared with younger adults. The goal of the present study is to test this hypothesis using population-based data. METHODS: The 1995 to 1999 National Automotive Sampling System data files were used. The National Automotive Sampling System is a national probability sample of passenger vehicles involved in police-reported tow-away crashes. BAI was defined according to the Abbreviated Injury Scale codes. Among those with BAI, information on occupant (age, seating position, restraint use), collision (collision type, delta-V, vehicle intrusion), and outcome characteristics were obtained and compared according to age. RESULTS: The overall incidence of BAI was 6.8 per 10,000 occupants and there was a steady increase in the BAI rate for advancing decades of life. The proportion of occupants with BAI who die at the scene of the collision is relatively consistent across all age groups ( approximately 85%). Among those who survive to receive medical care, ultimate survival is lowest among those aged 60 and older. Near-side collisions were responsible for more BAI among older adults than other age groups (50% vs. 20.6%, p < or = 0.05). Older adults sustained BAI in collisions with lower delta-V values compared with younger persons (p < or = 0.05). CONCLUSION: Older adults have the highest rate of motor vehicle collision-related BAI, and their injuries tend to occur in less severe collisions. A high level of suspicion for BAI among older adults should not be reserved for high-energy collisions only.