INSIGHT into the mechanism of the accidental damage to the cervical spine and spinal cord may be obtained from the evaluation of clinical and radiological data; from post-mortem investigations and from experiments, which are usually per formed on animals. Radiological signs result in various classifications of spinal injuries, for example that of Whitley and Forsyth (1960). During our meeting last year Roaf (1972) rightly criticised these classifications. The forces in two directions only are taken into account, usually. Nevertheless for clinical purposes, especially with regard to treatment, some classification is indispensable. Table I represents our classification of radiologically recognisable lesions of the lower cervical spine with the supposed mechanism-like disruptive and com pressive hyperfiexion and hyperextension.