This literature review analyzes biological aspects of depression after brain injury. Risk for suicide is examined among other issues. Research indicates that there appears to be about a 3 Ð 4 fold increased risk of suicide after a traumatic brain injury, although much of this increased risk may be due to pre-injury factors in terms of the characteristics of people who suffer these injuries. Approximately 1% of people who have suffered a traumatic brain injury committed suicide over a 15-year follow-up. Drug management of depression is discussed. (101 refs) (SC)