Summary:The literature on the diagnosis and treatment of minor closed head injury (CHI) in the computed tomography (CT) scan era was reviewed. Working definitions were developed for the categories of minor CHI (minimal, mild, and moderate), and the natural history of each category was reviewed. The risks of intracranial complications and surgical lesions were calculated for each category. For minimal CHI, they are almost no risks, for mild CHI, the risks are 15% and 2.5%, respectively. Patients with moderate CHI can expect an intracranial lesion rate of 30%; 8% require neurosurgical intervention. Additional evidence was documented from the literature to allow comparisons among various treatment options with reference to clinical outcomes. It is concluded that most patients with minimal CHI can be safely discharged from the Emergency Department (ED) unless risk factors, which might indicate the need for CT scanning or hospitalization, are present. Those having mild CHI should have urgent CT scanning; patients in whom the scan is normal can be safely discharged from the ED. Moderate CHI requires both hospital admission and urgent CT scanning. Based on the natural history evidence of similar risk in children and adolescents, the same recommendations are made in the pediatric age group with minor CHI. Cost factors and the public health impact of this management scheme are discussed.