Personality and behavioral change after traumatic brain injury (TBI) are often the most significant concerns for the families of TBI patients. This report examines discharge from military service after TBI for medical and behavioral criteria. When compared with the total discharge population (n = 1,879,724), the relative risk for behavioral discharge was 1.8 times greater for those with mild TBI (n = 1,778), and no difference for those with moderate (n = 174) or severe TBI (n = 274). Discharge for alcoholism or drug use was 2.6 times for mild TBI, 5.4 times for moderate TBI, and no difference for severe TBI compared with the total discharge population. Discharge for criminal conviction was 2.7 times for those with mild head injury, and no difference for those with moderate or severe TBI when compared with the total discharge population. Discharge for medical disability ranged from 7.5 times to 40.4 times, and mortality ranged from 11.6 to 142.4 times the total discharge population. Total sick days defined as the time from admission to return to duty or separation from service increased with head injury severity. Mean Injury Severity Score for mild TBI was 5.5, and 20.9 for severe TBI. Patients who sustain TBI should be monitored after injury for development of behavioral problems. The most effective way to reduce the cost of TBI is primary prevention of these injuries and examining military practices to reduce exposure to risk of TBI. Secondary and tertiary prevention measures such as evaluation and rehabilitation, where indicated, should be undertaken on a routine basis after TBI.