The authors describe the classification for traumatic rotary injuries of the cervical spine. The classification is based on a review of 306 severe lower cervical spine injuries observed in 255 patients between 1980 and 1994. Traumatic rotatory displacements (TRD) represented 39% of the 306 severe injuries. Three different lesions were observed: unilateral facet fractures, fracture-separation of the articular pillars, and unilateral facet dislocations.