To determine whether patients with traumatic brain injury (TBI) report higher levels of fatigue than do normal controls and to identify demographic and cognitive correlates of self-reported fatigue. Prospective study. Inpatient neurorehabilitation unit in a medical center and neurological institute. Forty-seven neurorehabilitation inpatients with TBI. Barrow Neurological Institute (BNI) Fatigue Scale and BNI Screen for Higher Cerebral Functions. Patients reported significantly greater levels of fatigue compared to the levels reported by normal controls, although fatigue was found to be unrelated to injury severity, number of days from injury to assessment, cognitive impairment, and gender. Inspection of individual items revealed no significant differences between severe versus moderate versus mild TBI groups. However, being able to last the day without taking a nap (ie, item 10) was found to be the most sensitive item associated with fatigue in the TBI group. Results of this study suggest the need to integrate activities and interventions to increase endurance in patients with TBI during early rehabilitation. Accommodating regular rest breaks and increasing restful sleep should be a focus of inpatient neurorehabilitation units.