The treatment of thoracolumbar spine fractures has been developed rapidly in the last ten years. A-0 internal fixator instrumentation is a posterior intrapedicular system developed by Dick in 1982. The advantages of this instrument are that it allows reduction in all three planes and provides stable fixation with short instrumentation. It also has the advantage to reduce the middle column effectively which is thought to be accomplished by ligamentotaxis. We analysed the clinical results of 52 patients with unstable fracture and fracture-dislocation of thoracolumbar spine who were treated with A-0 internal fixator instrument. We had clinincal and roentgenographical examination, preoperatively, postoperatively, and at the last follow-up examinations. The mean duration of follow-up was seventeen months. The results were as follows; 1. Burst fracture was the most common type in the spinal fractures of this series. 2. Excellent anatomic reduction was obtained by A-0 internal fixator instrument. 3. No significant loss 4. There was a close of reduction or loosening of the implant was found. relation between the recovery of neurologic deficit and the degree of the inital injury of the spine.