Background and Design.- Myelomeningocele results from failure of the embryonic neural folds to flex and fuse into a tube. Many central nervous sys¬tem and spinal colon abnormalities are associated with myelomeningocele. The aim of this study was to evaluate the associated central nervous system and spinal colon abnormalities in 17 children with myelo¬meningocele. Results.- Associated central nervous system ab¬normalities were found in 88% of the patients. These included Chiari II malformation, hydrocephalus, hid-romyelia, spinal lipoma, diplomyelia and agenesis of corpus callosum. Hydrocephalus was always associ¬ated with Chiari II malformation. In addition, 8 pati¬ents presented with alterations in the normal confi¬guration of their spinal colon. Conclusion.- Associated abnormalities were the main causes of late deterioration in myelomeningo¬cele patients. Most, possibly all, of this deterioration is preventable or correctable. Optimal care of these patients requires a comprehensive, coordinated plan of treatment by a multidisciplinary team.