Persistent thoracolumbar kyphosis in patients with achondroplasia is typically prevented with sitting modifications and bracing. When the kyphosis persists and progresses despite bracing, spinal fusion is indicated to prevent further progression and neurologic complications. Previous reports have suggested that instrumentation in such patients carries a high risk of neurologic injury. The purpose of this study was to evaluate the safety and efficacy of a two-stage procedure to control progressive kyphosis in the patient with achondroplasia. The authors treated four such patients (4-8 years old) surgically. The first stage involved an anterior spinal fusion with instrumentation and a posterior spinal fusion, and the second stage involved an additional posterior fusion. There were no neurologic complications. Correction ranged from 23.0% to 31.25%. All patients achieved a solid fusion. These results suggest that when nonoperative treatments fail, this procedure for thoracolumbar kyphosis in the achondroplastic patient can be done safely and effectively.