The association of head and cervical spine injury has long been recognized. Reports of the coincidence of these injuries in the literature range from 1.2 to 19%. This study was undertaken to determine the coincidence and examine the mechanisms of head and cervical spine injuries at a major trauma hospital. All cases of cervical spine injury (CSI) and head injury (HI) admitted to The Detroit Receiving Hospital during 1987 were identified using the hospital computer data bank and spine unit log book. There were 359 admissions for CSI including concussion, skull fracture, and intracranial hemorrhage. There were 92 admissions for CSI including complete or incomplete neurologic syndromes with fractures. There were 22 patients with both HI and CSI. Thus the coincidence of "primary" CSI with HI (both/CSI) is 24% while the coincidence of primary HI with CSI (both/HI) is 6%. The variety of injuries is demonstrated with appropriate imaging studies. Our study supports the view that all seriously head-injured patients should be treated as if a concomitant cervical spine injury is present until proven otherwise. It also shows that nearly one-quarter of patients with cervical spine injury have also experienced head injury. This coincidence may be an important consideration in the rehabilitation of such injured patients.