The goals of operation for unstable thoracolumbar spine injuries are decompression of any neural canal compression, restoration of normal anatomic contour of the spine and stabilization. A retrospective analysis on 64 thoracolumbar injured patients treated with internal instrumentation and fusion was performed from January 1991 to December 1996. The purpose of this study was to review the clinical outcome and efficacy of surgical treatment using internal instrumentation, and compare neurological, radiological and functional outcomes between anterior and posterior approach groups. Of these, 42 patients were operated via on posterior approaches and the other 22 patients by anterior approaches. At final follow up evaluation with mean period of 14.5 months, 50 patients(78%) were walking and 47 patients(92%) except 4 patients(A-A, three and C-C one patient) had improved using Frankel's grade in patients with neurological deficits(51 patients). No patient deteriorated. Radiological and functional outcomes were satisfactory in the majority of patients. In a comparison of the clinical outcomes between anterior and posterior approaches, there was no statistically significant difference in neurological outcome(the mean value of up-grade: anterior 1.05+/-.7, posterior 0.95+/-.9, p=0.42), but in radiological outcomes, there were no significant differences between the two groups in amount of restoration of vertebral compression(mean recovery rate: anterior 61.5%, posterior 50.9%), kyphotic deformity(mean recovery rate: anterior 47.9%, posterior 70.0%)(p>0.05), but the only difference was in the restoration of canal narrowing, with the anterior group more improved(recovery rate: anterior 86.4%, posterior 74.3%) (p<0.05). In functional outcomes by Prolo's scale, the anterior group was better than the posterior group(mean economic and functional status: anterior E(4.4), F(4.3); posterior E(3.5),F(3.9)). We conclude that agressive decompression, instrumentation and bone fusion has shown better clinical outcomes of the unstable thoracolumbar injured patients and the choice of surgical approaches depends on the general condition, age, status of bone mineral density, specific injury mechanism, radiological findings, and grade of neural injury at the time of injury of these patients.