Approximately 10% of all head injuries are caused during sport and about 10% of all sport-related injuries are head injuries. Most of these are minor head injuries. Many sports involve risk of repeated head injury. The classic punch-drunk syndrome in boxers reflects severe chronic traumatic encephalopathy. Recent research shows that repeated head injury can entail encephalopathy also in other types of athletes. They may experience symptoms such as headache, dizziness, irritability, memory deficit and concentration deficit. Neuropsychological testing reveals such cognitive deficits as impaired memory and attention, and reduced speed of information processing. Persistent sequelae can be prevented by correct management in the acute stage, appropriate follow-up, and prevention of repeated head injuries.