A review of the literature suggests that psychosocial disability in traumatic brain-injured (TBI) individuals and distress in families continues long after the initial injury. In this study the relationship of family stress to a number of factors was studied longitudinally. Caregivers of 51 TBI inpatients were interviewed at rehabilitation admission and by phone at 6, 12, and 24 months postinjury. Caregivers' most common complaints about their relatives were a lack of involvement in leisure activities, fatigue, slowness, and forgetfulness. Increasingly severe temper outbursts, anxiety, and self-centeredness were reported over time. Aggressiveness was reported by caregivers as moderate or severe in 31% of cases by 2 years postinjury. Of all complaints, only reports of inappropriate social behavior decreased over time. Despite caregivers' increasing complaints about their relatives, there were no trends toward greater self-reported stress over time. At the 2-year assessment, stress was significantly higher for caregivers of those with an at risk psychosocial history, and for those without sufficient funds for services. Caregivers reporting financial strain increased 22% from rehabilitation admission. Forty-seven percent of caregivers had altered or given up their jobs at 1 year postinjury, and 33% at 2 years postinjury. Although self-perceived measurements of stress did not increase over time, caregivers reported notable increases in medication use and substance use, and decreases in employment and financial status over the 2-year time period. When spouse and parent caregiver responses were compared, spouses reported a consistently greater number of behavioral problems, which increased in severity over time. Those behaviors associated with mood disturbances predominated.(ABSTRACT TRUNCATED AT 250 WORDS)