We evaluated self-rated functional status measured longitudinally in the year after injury in a geriatric trauma population. The longitudinal (L) group included 37 of 60 eligible trauma patients aged 65 years or older admitted December 2006 to November 2007 for greater than 24 hours who completed a Short Functional Status questionnaire (SFS) at 3, 6, and 12 months after injury. The SFS yields scores of 0 to 5 (5 = independent in all five activities of daily living [ADLs]) and has been validated among community-dwelling elders. The control (C) group included 63 trauma patients aged 65 years or older admitted December 2007 to July 2009 for greater than 24 hours who reported their preinjury functional status using the SFS at hospital admission. We used characteristics and scores of the C group to impute preinjury ADL scores for the L group. The groups were similar in baseline characteristics (age, ethnicity, Injury Severity Score, Charlson Comorbidity Index, and living arrangement; P > 0.05). For the C group, the preinjury ADL score was 4.6 (SD = 0.9). For the L group, ADL scores declined at all intervals reaching statistical significance at 12 months. We conclude that in the year after traumatic injury, geriatric patients lost the equivalent of approximately one ADL, increasing their risk of further functional decline, loss of independence, and death.