Surgical correction for kyphoscoliosis is increasingly being performed for patients with mucopolysaccharidosis (MPS). Reported case series have predominantly included patients with Type I (Hurler) and Type IV (Morquio) MPS. To their knowledge, the authors describe the first case report of surgical management of thoracolumbar kyphoscoliosis in Hunter syndrome (MPS Type II) and the rare occurrence of lumbar spondylolisthesis following surgical stabilization. A 12-year-old boy with Hunter syndrome presented with severe thoracolumbar kyphoscoliosis and no associated symptoms. Spinal radiographs demonstrated kyphosis of 48° (T11-L3) and scoliosis of 22° (T11-L3) with an anteriorly hypoplastic L-1 vertebra. The deformity progressed to kyphosis of 60° and scoliosis of 42° prior to surgical intervention. Spinal CT scans identified left T12-L1 facet subluxation, causing anterior rotatory displacement of the spine proximal to L-1 and bilateral L-5 isthmic spondylolysis with no spondylolisthesis. A combined single-stage anterior and posterior instrumented spinal arthrodesis from T-9 to L-4 was performed. Kyphosis and scoliosis were corrected to 4° and 0°, respectively. Prolonged ventilator support and nasogastric feedings were required for 3 months postoperatively. At 2.5 years following surgery, the patient was asymptomatic, mobilizing independently, and had achieved a solid spinal fusion. However, he had also developed a Grade II spondylolisthesis at L4-5; this was managed nonoperatively in the absence of symptoms or further deterioration of the spondylolisthesis to the 3.5-year postoperative follow-up visit. Satisfactory correction of thoracolumbar kyphoscoliosis in Hunter syndrome can be achieved by combined anterior/posterior instrumented arthrodesis. The risk of developing deformity or instability in motion segments adjacent to an instrumented fusion may be greater in patients with MPS related to the underlying connective tissue disorder.