Myelopathy due to compression of the cervical spinal cord by thickened dura developed in a patient with Maroteaux-Lamy syndrome. During the last trimester of pregnancy there was severe neurological deterioration with spastic quadriparesis and impairment of sphincter function. Two months after delivery there had been no improvement, so a cervical laminectomy and longitudinal splitting of the dura from C-5 to the foramen magnum was done. Good return of function resulted.