The AO spinal internal fixation system uses 5.0 mm diameter transpedicular Schanz screws with 7.0 mm diameter fully threaded stainless steel rods. Originally developed for the treatment of thoracolumbar and lumbar spine fractures, it can be used for a variety of spinal disorders. A prospective study has been carried out, and the first 48 patients have been reviewed. The results for those patients with fractures are excellent. In burst fractures, it has been possible to decompress the canal and restore lordosis. In only half of the cases of spondylolisthesis has it been possible to improve the degree of slip. The fixator has provided rigid stabilization for a variety of other spinal problems.