Rib fractures (RF) are noted in 4 to 12 per cent of trauma admissions. To define RF risks at a Level 1 trauma center, investigators conducted a 10-year (1995-2004) retrospective analysis of all trauma patients. Blunt chest trauma was seen in 13 per cent (1,475/11,533) of patients and RF in 808 patients (55% blunt chest trauma, 7% blunt trauma). RF were observed in 26 per cent of children (< 18 years), 56 per cent of adults (18-64 years), and 65 per cent of elderly patients (> or = 65 years). RF were caused by motorcycle crashes (16%, 57/347), motor vehicle crashes (12%, 411/3493), pedestrian-auto collisions (8%, 31/404), and falls (5%, 227/5018). Mortality was 12 per cent (97/808; children 17%, 8/46; adults 9%, 46/522; elderly 18%, 43/240) and was linearly associated with a higher number of RF (5% 1-2 RF, 15% 3-5 RF, 34% > or = 6 RF). Elderly patients had the highest mortality in each RF category. Patients with an injury severity score > or = 15 had 20 per cent mortality versus 2.7 per cent with ISS < 15 (P < 0.0001). Increasing age and number of RF were inversely related to the percentage of patients discharged home. ISS, age, number of RF, and injury mechanism determine patients' course and outcome. Patients with associated injuries, extremes of age, and > or = 3 RF should be admitted for close observation.