The neurological and neuroradiological manifestations of pediatric achondroplasia are analyzed on the basis of 10 cases. In addition to the classical symptomatology of an enlarging head, with or without increased intracranial pressure, several patients presented symptoms related to a small foramen magnum. Respiratory problems and quadriparesis were also observed in these patients. Six patients who were treated by foramen magnum decompression showed remarkable improvement. Neuroradiological evaluation revealed a significant number of patients with dilated cortical sulci and basal cisterns, and mild dilatation of the ventricles on computerized tomography (CT) and/or ventriculography. Two patients showed signs of obstruction at the fourth ventricle outlets. Some exhibited anomalous dilatation of cerebral veins and dural sinuses, narrowing of the sinuses at the jugular foramen, and enlarged emissary veins. Ventriculoperitoneal or ventriculoatrial shunts were placed in three patients. In the other children with a large head and dilated ventricles, head growth curves paralleled the normal slope, and there was no significant clinical evidence of increased intracranial pressure or enlarging ventricles on follow-up CT scan.