Recently, there have been progressive increase in use of internal fixator with transpedicular screws for treatment of unstable fractures and fracture-dislocations of thoracolumbar spine that offers several advantages such as short segmental fixation and early mobilization of the patient. The advantages of Harrington or Harri-Luque instrumentation used in the past were reported much but problems of short segmental fixation with transpedicular screws were reported sporadically. The authors have operated 51 cases of unstable thoracolumbar fractures and fracture-dislocations from October 1987 to September 1989. Among them, 25 cases were internally fixed with transpedicular screws.Twenty-three cases were followed up more than 1 year with average duration of 15 months (20 cases of C-D instrumentation and 3 cases of AO internal fixator). The following results were obtained. 1. Most of the patients were in the third to fifth decade of life and the most common cause of injury was fall from height. 2. Burst type fractures were most common (16 cases, 69%). 3. Complete reduction could be obtained in the burst and seat-belt type of injuries, but 4 out of 5 cases of fracture-dislocation type, complete reduction could not be obtained. 4. In burst fractures, the height of vertebral body was often collapsed during follow up period but as long as complete or incomplete reduction was obtained in fracture-dislocation type, the height of vertebral body was maintained. 5. Metallic failure was developed in 4 cases (17%). 6. Significant neurologic recovery was observed in cases of incomplete cord lesion.