The neurosurgical complications of mucopolysaccharidoses. Storage related disorders of mucopolysaccharides at the nervous system and the skeleton causes neurological dysfunctions. With the experience of treating five mucopolysaccharidoses cases during the last ten year, neurosurgical complications of the disease and treatment methods were investigated. Mainly, foramen magnum stenosis, narrowing of the unossified atlas ring, dysplasia of dens, atlanto-axial subluxation and soft tissue thickening at C1 were found. Other pathologies were not found responsible for the neurological impairement. Patients were surgically treated by craniovertebral junction decompression and stabilization. Because of partial recovery of serious neurological dysfuction, we advise prophylactic occipitocervival decompression and fusion.