From July, 1987 through June, 1989, 24 patients with thoracolumbar or lumbar idiopathic scoliosis were encountered at our hospital. Among them, 18 patients were adolescent idiopathic scoliosis, 6 were adult type. Their average curve was 54.4 degrees preoperatively. Anterior spinal fusion with Zielke instru-mentation was undergone for all patients, and the length of fusion did not extend beyond the major curve. The averaged curve correction was 80.8% in adolescent cases, and 57.3% in adult cases. The kyphogenic effect of the instru-mentation was not significant. The tilt angle of the vertebra at the lower end of the curve was reduced significantly. The fusion rate was 91.6%. Two of the patient developed pseudarthrosis. There was no major complication. The Zielke instrumentation system in the management of idiopathic thoracolumbar and lumbar scoliosis offers the advantages of a relatively good correction and mini-mal segment fusion.