The records of 34 patients who showed evidence of emotional deterioration 6 months or more following traumatic brain injury were compared with a group of patients matched for severity of initial neuropsychiatric impairment who did not show deterioration. The deterioration group was more likely to have been involved in assaults and less likely to have been involved in a motor vehicle accident than the improvement group. The deterioration group was also more likely to have a prior history of alcohol abuse and to have sustained a skull fracture with left parietal lobe injury than the improvement group. Agitation, hostility, apathy, lability of mood, emotional withdrawal, and depression were the symptoms most likely to worsen over time. This deterioration may have been due to premorbid personality characteristics or to the nature of long-term neuronal response to injury.