Objective: To examine whether increasing age is associated with poorer rehabilitation outcome. It was hypothesized that older individuals would benefit less from rehabilitation since increasing age is associated with greater morbidity and mortality. Design: Retrospective analysis of data collected at the beginning and end of inpatient medical rehabilitation. No experimental manipulation was performed. Injury severity, demographic information, initial level of functioning, and age were used in a hierarchical regression analysis to predict level of independent functioning. Setting: Inpatient traumatic brain injury units at four model system programs. Patients: 365 patients with traumatic brain injuries (39 mild, 67 moderate, 259 severe; 78% male; mean age=34 years). Interventions: All subjects participated in a comprehensive rehabilitation program including services from rehabilitation medicine, neuropsychology, nursing, social work, physical therapy, occupational therapy, speech and language pathology, vocational rehabilitation, and therapeutic recreation. Main Outcome Measures: Functional Independence Measure (FIM) and Disability Rating Scale (DRS). Results: After controlling for injury etiology, injury severity, and other demographic information, age had no statistically significant predictive value for functional outcome. Level of functioning on admission, independent of other factors, was the strongest predictor of functioning at discharge. Conclusions: Although increasing age has been strongly associated with higher rates of morbidity and mortality, it did not affect the level of functional improvement individuals achieved during inpatient rehabilitation. Hence, there does not appear to be justification for limiting access to rehabilitation solely on the basis of advanced age.