Alexander disease is a rare, degenerative disorder of the central nervous system. It is characterized clinically by spasticity, seizures, dementia, loss of developmental milestones, and macrocephaly. Here we describe a 13-year-old boy with Alexander disease and severe scoliosis. The patient initially presented at 9 months of age, with profound mental retardation and a history of seizures. When he was 7 years old, a pediatrician had diagnosed Alexander disease (hypotonia, macrocephaly, and progressive low-density white matter predominantly in the frontal region on computed tomography examination). From the age of 10, thoracolumbar scoliosis had gradually become severe. Because treatment using a corrective brace would have produced major problems because of the patient's mental retardation, the scoliosis was successfully treated surgically, by careful posterior spinal fusion with instrumentation, and an autologous iliac crest bone graft. A 64°curve was corrected to 18° (72% correction). Scoliosis with Alexander disease is considered to be very rare because patients with the disease seldom survive long enough to develop spinal deformities.