Objective: To investigate incidence and etiology of rehospitalizations at 1, 2, and 3 years after traumatic brain injury. Design: Descriptive statistics were computed in a prospective study of etiology and incidence of rehospitalization at years 1, 2, and 3 postinjury. Analysis of variance (ANOVA) and χ2 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: Four 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: Six hundred sixty-five rehabilitation patients admitted to acute care within 24 hours of traumatic brain injury between 1989 and 1996. Main Outcome Measures: Annual incidence and etiology of rehospitalization. Results: The annual incidence of rehospitalization ranged from 20% to 22.5%. Approximately half the rehospitalizations were for elective reasons. The most common reason for rehospitalization was for orthopedic or reconstructive surgery, followed by infectious disorders and general health maintenance. After the first year, the incidence of readmissions for seizures and psychiatric difficulties increased substantially. ANOVA and χ2 analyses were performed on data from the first year postinjury. No statistically significant associations were noted between incidence and etiology of rehospitalization and: demographics; injury severity; payer source for rehabilitation; concurrent injuries; acute care and rehabilitation length of stays; discharge Functional Assessment Measure; and discharge residence (p > .05). Conclusions: There is a relatively stable but high rate of rehospitalization for at least 3 years after injury. The costs of rehospitalization should be considered when evaluating the long-term consequences of injury.