A gunshot injury of the spine is an unusual injury in Taiwan. Both the direct path of the bullet and its concussive effects can cause injury to the spinal cord and spinal column. In the emergency department (ED), a thorough evaluation with a history, physical examination and appropriate radiographic studies are the keys to effective treatment. Principles of treatment include spinal stability, aggressive rehabilitation, prevention of infection and preservation of neurologic function. We describe a 20-year-old woman with a gunshot injury to the spine caused by a low-velocity weapon. The bullet penetrated the thecal sac via the left flank region and wandered freely in the subarachnoid space. The patient developed cauda equine syndrome including weakness of the left lower leg, sensory deficit and loss of bladder function immediately after the injury. A two-dimensional abdominal computed tomographic scan showed a bullet in the spinal canal (L5 level). Intradural upward migration of the bullet was noted intraoperatively. The patient had complete relief of symptoms by 2 months following surgery.