Head injury and the mechanisms whereby the energy involved is injuriously transferred to the brain and central nervous system are defined. There is a paucity of hard data and better retrieval is required. Good protection alters injury patterns and caution is necessary in the simplistic interpretation of post-mortem studies. The major numerical and financial burden is minor head injury. Though eminently preventable, these injuries carry significant, severe, physical, intellectual, behavioural, social and economic sequelae. The great proportion of head injury is avoidable by relatively simple means. Good head protection is available, the failure is in its use in practice. Preventable injury is unacceptable injury — the more so in today's necessarily competitive conditions. Present objections to good protective practice, the medical requirements for protection and wearer's criteria for acceptable designs are presented.