The functional and morphological aspects of craniosynostoses are reviewed, based on a series of 462 operations, 350 intra-cranial pressure recordings and 300 I.Q. assessments. Increased intracranial pressure and mental impairment are linked. The frequency of intracranial hypertension is higher when more than one suture is involved, but even monosutural craniosynostoses can be affected. Increased intracranial pressure had mental deficiency are more frequent after one year of age than before. Surgery lowers the intracranial pressure and halts the mental regression. The younger the patient is at the time of surgery, the better the results. Surgery does not improve the I.Q. once it is already impaired. Morphological results of frontocranial remodeling are good and remain so with growth. Facial anomalies associated with craniosynostoses improve after early frontocranial remodeling, except for the severe midface retrusion of Crouzon's disease and Apert's syndrome that need in most cases a supplementary midface advancement.