The authors emphasize the possible complications following the surgical operation by ventriculocaval or ventriculoperitoneal shunts in the neonatal hydrocephalus. These complications are mainly caused by the liquoral hyperdrenage which occurs for the differential pressure of the valve system, since this valve is operating by the differential pressure between cerebral ventricles and the receiving cavities and not by the absolute pressure existing in the ventricular cavity. The following late complications are examined: a) chronic subdural haematoma; b) slit ventricle syndrome. Their evolution often is deceitful and severe problems of differential diagnosis with others pathological infantile states arise.