Segmental Spinal Instrumentation(S.S.I.) is more effective means of managing unstable thoraco-lumbar spine fractures than traditional Harrington Rod Instrumentation as an operative procedure which afforded rigid internal fixation with stability and needed minimal external immobilization. Early return to normal activity and successful rehabilitation are facilitated by efficient stabilization with S.S.I. Fifty-nine patients with fractures and fracture-dislocations of thoraco-lumbar spine were treated by Harrington Rod Instrumentation (29 patients) and S.S.I. (30 patients) at this hospital from June 1979 to July 1984. We have analysed the results of these treatment and obtained following conclusions: 1. S.S.I. is more rigid internal fixation than Harrington Rod Instrumentation. a) no or minimal external immobilization b) early ambulation and rehabilitation c) lowered complications 2. There was no significant difference in correction rate, loss of correction, and neurologic recovery between Harrington Rod Instrumentation and S.S.I.