As a result of the authors’ experience they advocate posterior fossa decompression in patients with myelomeningocele at the first sign of compression of brain stem or the cervical cord or both. If decompression is not undertaken at once the impaired gag and cough reflexes place the child at risk. He may develop pneumonia. If decompression is delayed too long full neurological recovery will not occur. The removal of bone and the opening of dura must be carried down to the bottom of the tonsillar tip, sometimes as low as C7. The most dramatic improvement occurs in infants whose symptoms are life threatening. Less dramatic but just as real is the improvement in older children. Although investigations such as myelography and ventriculography will show the malformation, they are not essential. The associated visible malformations and the clinical condition are the most reliable means of making the diagnosis. Delaying the decompression risks the life of the infant and threatens the quality of life for the older child.