The author considers two main concepts of minimal brain dysfunction: 1) a continuum notion, in which minimal brain dysfunction is viewed as a lesser variant of gross traumatic brain damage, and 2) a syndrome notion, in which minimal brain dysfunction constitutes a genetically determined disorder rather than a response to any form of injury. The evidence on the former indicates that subclinical damage to the brain may occur and may involve psychological sequelae-but the damage probably has to be rather severe, and the result is not a homogeneous syndrome. The second alternative remains a possibility, but the claims far outrun the empirical findings that could justify them.