Three patients with hyperflexion sprain of the cervical spine secondary to motor vehicle accidents are discussed. One patient exhibited tetraplegia and the other two only had paresthesia of the upper and/or lower extremities at the scene of the accident. All patients were young with no evidence of degenerative disc disease or osteoarthritis. Diagnosis of hyperflexion sprain is suggested by transient or persistent neurological deficits, local tenderness, or plain film findings, which include interspinous fanning, localized kyphotic angulation, subluxation, or disc space narrowing. Review of our patients' records revealed that some of these findings were evident at their initial presentation. In patients who have no neurological deficits, controlled flexion and extension views after routine plain films may be diagnostic of an unstable cervical spine. If there is a persistent neurological deficit, a magnetic resonance imaging scan is the examination of choice. If there is no compression of the thecal sac or spinal cord, supervised flexion and extension views of cervical spine should be done. Definitive management of the unstable spine is operative fixation.