Despite many attempts it has so far not been possible to establish a uniform application of the term "whiplash injury" either for diagnostics, therapy, or medical reports. To obtain a clear, functionally based definition, the most frequently used formulations are compared, taking into account anatomic and mechanical aspects in addition. Whiplash injury is separated from hyperextension injury ("snap" trauma of the cervical spine), even though overlaps in the lesion picture are possible. In the definition suggested, invariable linkage to rear-end collision is dispensed with. Instead, it is emphasized that this accident mechanism is frequent, but can also be substituted. In contrast to other definitions, special emphasis is laid on the biphasic course since a substantial traumatization is to be assumed to occur from the secondary movement. This second movement does not by any means proceed with low energy, but its determined by the mass contraction of the muscle group subject to primary abrupt overextension with their synergists. On the basis of the analysis of the mechanical course and the investigation of a actual accidents, the monosegmental cervical spine injury cannot, therefore, be seen as the characteristic type of damage due to a whiplash injury. Instead of this, the frequent occurrence of multiple injuries is pointed out.