This is a comprehensive review of the late-occurring effects of traumatic brain injury (TBI). It appears that TBI increases the risk over basal rates for the general population, to this degree: for depression, by a factor of five or 10; for seizures, by two to five; for psychotic disorders, by the same factor; and for dementia, by four or five. Severe TBI, or injuries with special characteristics, may increase the risk of delayed sequelae even further. One is not able, at this point, to estimate the relative occurrence of a newly described entity-delayed amnesia. An initial TBI increases the risk for subsequent TBI, by a factor of two. A second TBI increases the risk of yet another TBI eightfold.