 Background Concussion is an important public health concern. Debilitating and persistent post-concussional symptoms are associated with considerable long-term sickness and markedly reduced health-related quality of life in industrialized countries. In Denmark, approximately 25000 people are diagnosed with concussion each year. Although complete resolution of typical post-concussional symptoms such as headaches, dizziness and fatigue normally occur within the first days or weeks after a concussion, a significant proportion corresponding to five to15 of patients continue to experience symptoms longer than 3 months post-injury. These patients are at risk of long-term sickness, reduced health-related quality of life as well as permanently reduced working ability, which is particularly disastrous for adolescents and young adults. Currently, no standardised treatment is available for patients with persistent post-concussional symptoms. 