Whiplash, or post-traumatic, neck injury is an increasingly frequent clinical problem. Large numbers of patients present with both acute and chronic physical symptoms. It has frequently been alleged that psychological factors and social variables (especially the influence of possible compensation) are major causes of persistent physical complaints and disability. There have been few methodologically satisfactory studies, and very little attention has been paid to mental state and quality of life issues. Epidemiology, clinical features, prognosis, and aetiology are all reviewed with a special emphasis on psychological outcome and variables. It is argued that such factors are as important in relation to whiplash injuries as are other physical conditions, especially musculoskeletal disorders. In addition, specific posttraumatic symptoms are common but usually unrecognized.