Segmental Spinal Instrumentation is effective operative procedure in unstable fracture and fracture-dislocation of the thoracolumbar spine, providing rigid spinal stability and reduces needs of external support and complications. Fifty nine patients with unstable fracture and fracture-dislocation of thoracolumbar spine were treated with Harrington rod instrumentation and sublaminar wiring(31 patients) and Luque rod instrumentation with sublaminar wiring(28 patients) in Hyun Dai Hae Seong Hospital, Ulsan, Paik Hospital, Pusan from Dec. 1983 to April 1986. We have analyzed the results of treatment about two type of S.S.I. and obtained following conclusions; l. In 59 patients, T12 level injury was 17 cases, Ll level was 25 cases and so T12 and Ll involvement were 71%. 2. By Francis Denis classification, 28 cases were burst type fracture, 20 cases were fracture-dislocation type, 6 cases were seat belt type and 5 cases were wedge compression type. 3. In Harrington rod with S.S.I., initial kyphotic angle was 22.4° and postoperative angle was 7.4° and correction rate was 66.9%; in Luque rod with S.S.I., preoperative kyphotic angle was 21.7° and postoperative angle was 6.5° and correction rate 69.6%. So there was no difference of correction rate in two type of S.S.I. 4. In Harrington rod with S.S.I., the loss of reduction was 1.2° and the loss was 7%; in Luque rod with S.S.I., the loss of reduction was 7.2° and the loss rate was 48%. So the loss of reduction of Luque rod with S.S.I. was greater than that of Harrington rod with S.S.I. 5. After removal of implants, Luque rod with S.S.I. patients have better range of motion than Harrington rod with S.S.I. patients clinically, but it needs more follow-up because of a few cases(18 cases).