Objective: To investigate the incidence and cause of rehospitalizations 1 and 5 years after traumatic brain injury. Design: Descriptive statistics were computed in a prospective study of the cause and incidence of rehospitalizations at years 1 and 5 after injury. Analysis of variance and chi-square tests were used to identify factors relating to rehospitalization; factors included length of stay, admission and discharge functional status, payer source, medical complications, injury severity, and demographics. Setting: Seventeen medical centers in the federally sponsored Traumatic Brain Injury Model Systems. In each setting, the continuum of care includes emergency medical services, intensive and acute medical care, inpatient rehabilitation, and a spectrum of community rehabilitation services. Participants: Eight hundred ninety-five rehabilitation patients admitted to acute care within 24 hours of traumatic brain injury between 1989 and 1999 were examined at 1-year follow-up. Main Outcome Measures: Incidence and cause of rehospitalization at 1 and 5 years after injury. Results: The incidence of rehospitalization ranged from 22.9% 1 year after injury to 17.0% at 5 years after injury. At 1 year after injury, a third of the rehospitalizations were for elective reasons. At 5 years after injury, the incidence of readmissions for seizures and psychiatric difficulties and general health maintenance increased substantially. T-tests and chi-square analyses were performed on the 5-year follow-up data to compare those rehospitalized for unplanned reasons with those not rehospitalized. Conclusions: There remains a relatively high rate of rehospitalization in the long term after traumatic brain injury. The costs of rehospitalization should be considered when evaluating the long-term consequences of injury.