This paper evaluates the efficacy the Moss-Miami System instrumentation for surgical treatment of spinal deformity. Eight-five patients with AIS underwent a posterior spinal fusion with using this system between 1994 and 1998. Radiographs of the spine were taken preoperatively, at discharge, one year after surgery, and at the latest follow-up (average of 2.5 year, range 2 to 6 years). All radiographs were assessed for curve magnitude, coronal balance, kyphosis, lordosis, junctional kyphosis, and sagittal balance. The Scoliosis Research Society instrument was administered at the final follow-up. The average curve correction ranged from 53 to 65 percent. All patients showed solid fusion by final follow-up. Three patients required a second operation for complications related to their scoliosis; two patients showed a rod fracture without evidence of pseudoarthrosis or curve progression. Two transient neurological complications related to the surgery were observed. SRS results were favorable with regard to function and cosmetic appearance.